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ABSTRACT: Brimacomb, OE, Martinez, MP, McCormack, WP, and Almstedt, HC. A 2-year longitudinal study of bone mineral density in collegiate distance runners. J Strength Cond Res 37(8): 1654-1659, 2023-The purpose of this investigation was to examine changes in bone mineral density (BMD) of male and female collegiate distance runners over 2 years. Bone mineral density of 29 collegiate distance runners (16 men and 13 women) were measured 5 times over 24 months using dual-energy x-ray absorptiometry (DXA) at the anterior-posterior (AP) and lateral (LAT) spine, femoral neck (FN), total hip (TH), whole body (WB), and ultradistal (UD) forearm. Repeated-measures multivariate analysis of covariance, with bone-free lean mass (BFLM) as covariate, was used to compare mean BMD values. Adjusted for BFLM, there were no significant differences ( p > 0.05) in BMD at any site between sexes. There were no significant differences at the AP or LAT spine, FN, or WB between visit 1 and 5 for either sex. There was a significant increase in BMD ( p = 0.044) at the UD forearm over 2 years in males. However, 56% of the men ( n = 9) had a Z-score < -1.0 at the UD forearm. Seven of 11 women had Z-scores < -1.0 at the LAT spine and 4 of 13 had Z-scores < -1.0 at the AP spine. There were no significant changes in BMD at any site over the 2-year time frame, except a significant increase in BMD at the nondominant forearm in men. The spine appears to be an area of concern for women in this study when examining Z-score results. Coaches and medical staff need to continually educate collegiate endurance athletes about the importance of achieving and maintaining BMD through their college years.
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Densidad Ósea , Huesos , Femenino , Masculino , Humanos , Estudios Longitudinales , Absorciometría de Fotón/métodos , Columna VertebralRESUMEN
Objective: Research investigating the dietary habits of distance runners has presented varying results. Proper dietary intake appears to enhance distance running performance and low dietary intake may impact health. The purpose of this investigation was to perform a comprehensive evaluation of nutrient intake of collegiate distance runners with comparison to recommendations for athletes.Methods: Twenty-one men (Age: 19.6 ± 1.2 years; height: 177.1 ± 5.7 cm; body mass: 65.7 ± 4.6 kg; body fat: 15.5 ± 2.2%) and 20 women (Age: 20.2 ± 1.7 years; height: 162.9 ± 6.6 cm; body mass: 53.7 ± 6.5 kg; body fat: 23.3 ± 3.6%) volunteered to participate in the investigation. Energy intake was derived from the Block Food Frequency Questionnaire. Energy availability was calculated by subtracting exercising energy expenditure from daily energy intake, divided by bone free lean mass and fat-free mass. Macronutrient and micronutrient consumption were compared with the appropriate dietary reference intake values, U.S. Dietary Guidelines, or standards recommended for endurance athletes.Results: Dietary intake for the men was 2,741.0 ± 815.2kilocalories and for the women was 1,927.7 ± 638.2kilocalories. A majority of the runners (73%) consumed less than recommended levels of carbohydrates. All men and 75% of women met or exceeded the recommended daily protein intake. Fifty percent of women and 24% of men did not meet the recommended daily allowance for calcium. Ninety-five percent of the runners did not meet the RDA for vitamin D. All the men and 75% of the women met the RDA for iron intake, with 24 of the runners taking an iron supplement. Eight men and 10 women did not meet the recommended intake for potassium.Conclusion: The dietary intake in this group of distance runners is below that necessary for the level of energy expended in their training. Carbohydrate intake is below the recommended amount for endurance athletes, and the calcium and vitamin D intake may not be favorable for bone health in this group of distance runners.
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Atletas , Ingestión de Energía , Estado Nutricional , Ingesta Diaria Recomendada , Carrera , Fenómenos Fisiológicos en la Nutrición Deportiva , Carbohidratos de la Dieta/administración & dosificación , Proteínas en la Dieta/administración & dosificación , Metabolismo Energético , Femenino , Humanos , Masculino , Estudiantes , Oligoelementos/administración & dosificación , Universidades , Vitaminas/administración & dosificación , Adulto JovenRESUMEN
Strength, muscle mass, and muscle quality have been observed to be compromised in low body-mass index individuals such as competitive runners, increasing their risk for sarcopenia. The purpose was to compare indices of sarcopenia in young runners to age, height, body-mass, and body-mass index-matched non-runners. Handgrip strength and arm composition from dual-energy x-ray absorptiometry (baseline-T1, T2=5.3±1.4, T3=11.5±0.7 months later) were assessed in 40 non-runners and 40 runners (19.3±0.7 vs. 19.2±1.1 years, 170.7±10.3 vs. 171.1±9.1 cm, 60.2±7.4 vs. 60.2±7.9 kg, 20.6±0.9 vs. 20.5±1.5 kg m-2). The unitless variable of muscle quality, was defined as the sum of right and left maximal handgrip (in kg) divided by the sum of bone-free lean mass of both arms (in kg). Female runners displayed the highest muscle quality (T1=15.3±1.7; T3=15.7±2.0) compared to male runners (T1=13.7±1.4, p < 0.001; T3=14.2±1.6, p < 0.001) and male non-runners (T1=12.4±1.8, p=0.001; T3=13.2±1.6, p < 0.001), while female non-runners (T1=14.6±2.5, p=0.154; T3=15.1 ±2.2, p=0.124) showed higher muscle quality than male non-runners. Higher muscle quality in low-body-mass index females persists over one-year during young-adulthood and while running contributes to whole-body muscle mass accrual, it does not appear to be significantly associated with improvements in the most commonly used upper-body diagnostic indicator of sarcopenia.
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Índice de Masa Corporal , Músculo Esquelético/anatomía & histología , Músculo Esquelético/fisiología , Carrera/fisiología , Sarcopenia/fisiopatología , Caracteres Sexuales , Estatura , Femenino , Fuerza de la Mano , Humanos , Estudios Longitudinales , Masculino , Fuerza Muscular , Estudios Prospectivos , Factores de Riesgo , Sarcopenia/etiología , Adulto JovenRESUMEN
PURPOSE: Weight-bearing activities such as running have been shown to be osteogenic. However, investigations have also shown that running may lead to site-specific deficiencies in bone mineral density (BMD) as well as overall low BMD. The purpose of this investigation was to evaluate and compare the BMD of female and male collegiate cross-country runners with non-running controls. In addition, energy availability and disordered eating attitudes and behaviors were assessed. METHODS: BMD of 60 collegiate cross-country runners and 47 BMI and age-matched non-running controls were measured via DXA scans. Participants completed a Block 2014 Food Frequency Questionnaire and Eating Disorder Examination Questionnaire. RESULTS: Controlling for fat-free mass (FFM), male runners showed greater BMD at the femoral neck (0.934 ± 0.029 vs. 0.866 ± 0.028 g cm2, p < 0.05), total hip (1.119 ± 0.023 vs. 1.038 ± 0.021 g cm2, p < 0.05), and whole body (1.119 ± 0.023 vs. 1.038 ± 0.021 g cm2, p < 0.05) than male controls. The female runners had greater whole-body BMD than female controls (1.143 ± 0.018 vs. 1.087 ± 0.022 g cm2, p < 0.05). Runners scored significantly higher than controls in dietary restraint (1.134 ± 1.24 vs. 0.451 ± 0.75, p < 0.05), male runners were significantly higher than male controls in eating concern (1.344 ± 1.08 vs. 0.113 ± 0.27, p < 0.05) and female runners were significantly higher than male runners in shape concern (1.056 ± 1.27 vs. 0.242 ± 0.31, p < 0.05). Forty-two percent of the male runners and 29% of female runners had an energy availability of less than 30 kcals kg-1FFM. CONCLUSION: It appears that distance running has beneficial effects on whole-body BMD and site-specific areas. Further research is warranted to further clarify the health effects of eating behaviors and EA of distance runners.
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Densidad Ósea , Dieta , Metabolismo Energético , Carrera/fisiología , Adulto , Femenino , Humanos , MasculinoRESUMEN
INTRODUCTION: The aim of this study was to examine the relationship between serum C-terminal agrin fragment (CAF) concentrations and neuromuscular fatigue in older adults. METHODS: Twenty-two healthy older men and women volunteered for this study. Resting fasted blood samples were collected and prepared for measurement of serum CAF concentration by a commercially available ELISA kit. The onset of neuromuscular fatigue was measured by monitoring electromyographic fatigue curves from the vastus lateralis muscle using the physical working capacity at fatigue threshold (PWCFT ) test. RESULTS: A significant inverse correlation for men was observed between CAF and PWCFT (r = -0.602; P = 0.05), but not for women (r = 0.208; P = 0.54). After controlling for age and body mass index, significant correlations (r = -0.69; P = 0.042) remained for men, but not for women (r = 0.12; P = 0.76). CONCLUSIONS: These data suggest that serum CAF concentrations were significantly related to the onset of neuromuscular fatigue independent of age and BMI in men only.
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Agrina/sangre , Fatiga/sangre , Fatiga/fisiopatología , Fatiga Muscular , Anciano , Anciano de 80 o más Años , Envejecimiento , Agrina/química , Electromiografía , Ergometría , Femenino , Humanos , Masculino , Persona de Mediana Edad , Músculo Esquelético/fisiopatologíaRESUMEN
OBJECTIVE: To examine the efficacy of l-alanyl-l-glutamine ingestion with a commercially available sports drink compared to the sports drink only on time to exhaustion and physiological measures during prolonged endurance exercise. METHODS: Twelve endurance-trained men (23.5 ± 3.7 years; 175.5 ± 5.4 cm; 70.7 ± 7.6 kg) performed 4 trials, each consisting of a 1-hour treadmill run at 75% VO2peak followed by a run to exhaustion at 90% VO2peak. One trial consisted of no hydration (NHY), another required ingestion of only a sports drink (ED), and 2 trials required ingestion of a low dose (LD; 300 mg·500 ml(-1)) and high dose (HD) of l-alanyl-l-glutamine (1 g·500 ml(-1)) added to the sports drink. During the fluid ingestion trials, 250 ml was consumed every 15 minutes. Plasma glutamine, glucose, electrolytes, and osmolality were measured prior to the run (PRE) and at 30, 45, and 60 minutes. VO2, respiratory quotient (RQ), and heart rate (HR) were measured every 15 minutes. RESULTS: Time to exhaustion was significantly longer during the LD and HD trials compared to NHY. No differences were noted in time to exhaustion between ED and NHY. Plasma glutamine concentrations were significantly elevated at 45 minutes in LD and HD trials and remained elevated at 60 minutes during HD. Sodium concentrations increased from the beginning of exercise and remained stable for the duration of the 1-hour run. At 60 minutes, plasma sodium was significantly lower in all trials compared to NHY. CONCLUSIONS: Results indicated that ingestion of the alanine-glutamine dipeptide at either the low or high dose significantly improved time to exhaustion during high-intensity exercise compared to a no-hydration trial.
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Alanina/administración & dosificación , Dipéptidos/administración & dosificación , Ejercicio Físico/fisiología , Glutamina/administración & dosificación , Resistencia Física/efectos de los fármacos , Adulto , Bebidas , Glucemia/análisis , Electrólitos/sangre , Fatiga/prevención & control , Glutamina/sangre , Humanos , Masculino , Concentración Osmolar , Consumo de Oxígeno , Carrera/fisiología , Fenómenos Fisiológicos en la Nutrición Deportiva , Factores de Tiempo , Adulto JovenRESUMEN
The purpose of this investigation was to determine which physiological assessments best predicted high-intensity running (HIR) performance during a women's collegiate soccer game. A secondary purpose was to examine the relationships among physiological performance measures including muscle architecture on soccer performance (distance covered, HIR, and sprints during the game) during a competitive collegiate women's soccer game. Ten National Collegiate Athletic Association (NCAA) Division I women soccer players performed physiological assessments within a 2-week period before a competitive regulation soccer game performed during the spring season. Testing consisted of height, body mass, ultrasound measurement of dominant (DOMleg), and nondominant leg (NDOMleg) vastus lateralis for muscle thickness (MT) and pennation angle (PA), VO2max, running economy, and Wingate anaerobic test (WAnT) for peak power (PP), mean power (MP), and fatigue rate (FR). During the game, distance run, HIR, and sprints were measured using a 10-Hz global positioning system. Stepwise regression revealed that VO2max, dominant leg thickness, and dominant leg PA were the strongest predictors of HIR distance during the game (R = 0.989, SEE = 115.5 m, p = 0.001). V[Combining Dot Above]O2max was significantly correlated with total distance run (r = 0.831; p = 0.003), HIR (r = 0.755; p = 0.012), WAnTPP (r = -0.737; p = 0.015), WAnTPP·kg (r = -0.706; p = 0.022), and WAnTFR (r = -0.713; p = 0.021). DOMlegMT was significantly correlated with WAnTFR (r = 0.893; p = 0.001). DOMlegPA was significantly correlated with WAnTFR (r = 0.740; p = 0.023). The NDOMlegPA was significantly correlated to peak running velocity (r = 0.781; p = 0.013) and WAnT MP·kg (r = 0.801; p = 0.01). Results of this study indicate that V[Combining Dot Above]O2max and muscle architecture are important characteristics of NCAA Division I women soccer players and may predict HIR distance during a competitive contest.
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Aceleración , Rendimiento Atlético , Contracción Muscular/fisiología , Resistencia Física/fisiología , Carrera/fisiología , Fútbol/fisiología , Atletas , Estudios de Cohortes , Femenino , Humanos , Fatiga Muscular , Músculo Esquelético/diagnóstico por imagen , Músculo Esquelético/fisiología , Consumo de Oxígeno/fisiología , Esfuerzo Físico/fisiología , Valor Predictivo de las Pruebas , Factores de Tiempo , Ultrasonografía , Adulto JovenRESUMEN
The relationships between 30-m sprint time and performance on a nonmotorized treadmill (TM) test and a vertical jump test were determined in this investigation. Seventy-eight physically active men and women (22.9 ± 2.7 years; 73.0 ± 14.7 kg; 170.7 ± 10.4 cm) performed a 30-second maximal sprint on the curve nonmotorized TM after 1 familiarization trial. Pearson product-moment correlation coefficients produced significant (p ≤ 0.05) moderate to very strong relationships between 30-m sprint time and body mass (r = -0.37), %fat (r = 0.79), peak power (PP) (r = -0.59), relative PP (r = -0.42), time to peak velocity (r = -0.23) and TM sprint times at 10 m (r = 0.48), 20 m (r = 0.59), 30 m (r = 0.67), 40 m (r = 0.71), and 50 m (r = 0.75). Strong relationships between 30-m sprint time and peak (r = -0.479) and mean vertical jump power (r = -0.559) were also observed. Subsequently, stepwise regression was used to produce two 30-m sprint time prediction models from TM performance (TM1: body mass + TM data and TM2: body composition + TM data) in a validation group (n = 39), and then crossvalidated against another group (n = 39). As no significant differences were observed between these groups, data were combined (n = 72) and used to create the final prediction models (TM1: r = 0.75, standard error of the estimate (SEE) = 0.27 seconds; TM2: r = 0.84, SEE = 0.22 seconds). These final movement-specific models seem to be more accurate in predicting 30-m sprint time than derived peak (r = 0.23, SEE = 0.48 seconds) and mean vertical jump power (r = 0.31, SEE = 0.45 seconds) equations. Consequently, sprinting performance on the TM can significantly predict short-distance sprint time. It, therefore, may be used to obtain movement-specific measures of sprinting force, velocity, and power in a controlled environment from a single 30-second maximal sprinting test.
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Rendimiento Atlético/fisiología , Prueba de Esfuerzo , Carrera/fisiología , Adiposidad , Adulto , Peso Corporal , Prueba de Esfuerzo/instrumentación , Femenino , Humanos , Masculino , Modelos Teóricos , Valor Predictivo de las Pruebas , Adulto JovenRESUMEN
The purpose of this randomized, cross-over design study was to examine the effect of three different muscle potentiation protocols on acute changes in muscle architecture and vertical jump performance. Eleven experienced, resistance trained men (25.2±3.6y) completed three potentiation squat protocols using moderate intensity (MI; 75%, 3 sets x 10 repetitions), high intensity (HI; 90%, 3 sets x 3 repetitions) and 100% (1RM; 1 set x 1repetition) of their 1RM. In addition, all participants completed a control session (CTL) in which no protocol was performed. During each testing session, muscle architecture and vertical jump testing were assessed at baseline (BL), 8min post (8P) and 20min post (20P) workout. Ultrasound measures included cross sectional area (CSA) and pennation angle (PANG) of both the rectus femoris (RF) and vastus lateralis (VL). Following each ultrasound measure, peak vertical jump power (PVJP) and mean (MVJP) power was assessed using an accelerometer. Magnitude based inferences were used to make comparisons between trials. The MI trial resulted in a likely greater increase from BL to 8P and 20P in RF-CSA and VL-CSA, while the HI trial resulted in a likely greater change from BL to 20P in both RF-CSA and VL-CSA. Meanwhile, changes in PVJP and MVJP for the MI trial was likely decreased at BL-8P and BL-20P, while the HI trial was shown to result in a likely or possible decrease compared to CTL at BL-8P and BL-20P, respectively. A likely negative relationship was observed between changes in VL-PANG and MVJP (r = -0.35; p , 0.018) at BL-8P, and between changes in PVJP and RF-CSA (r = -0.37; p , 0.014) at BL-20P. Results of this study were unable to demonstrate any potentiation response from the trials employed, however these protocols did result in acute muscle architectural changes. Key pointsThree squat protocols using moderate intensity (75% 1-RM; 3 sets x 10 repetitions), high intensity (90% 1-RM, 3 sets x 3 repetitions) and maximal intensity (100% 1RM; 1 set x 1repetition) were unable to potentiate jump height or jump power in experienced, resistance trained men.Experienced, resistance trained athletes who are not competitive may be limited in regards to potentiation due to a poor level of conditioning.Both the moderate and high intensity potentiation protocols stimulated acute changes in muscle architecture. Greater increases in the CSA of both the RF and VL muscles were noted.A different potentiation protocol may have elicited greater changes in muscle architecture.
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Recently, the Dynavision™ D2 Visuomotor Training Device (D2) has emerged as a tool in the assessment of reaction time (RT); however, information regarding the reliability of the D2 have been limited, and to date, reliability data have been limited to non- generalizable samples. Therefore, the purpose of this study was to establish intraclass correlation coefficients (ICC2,1) for the D2 that are generalizable across a population of recreationally active young adults. Forty-two recreationally active men and women (age: 23.41 ± 4.84 years; height: 1.72 ± 0.11 m; mass: 76.62 ± 18.26 Kg) completed 6 trials for three RT tasks of increasing complexity. Each trial was separated by at least 48-hours. A repeated measures ANOVA was used to detect differences in performance across the six trials. Intraclass correlation coefficients (ICC2,1) standard error of measurement (SEM), and minimal differences (MD) were used to determine the reliability of the D2 from the two sessions with the least significant difference score. Moderate to strong reliability was demonstrated for visual RT (ICC2,1: 0.84, SEM: 0.033), and reactive ability in both Mode A and Mode B tasks (Mode A hits: ICC2,1: 0.75, SEM: 5.44; Mode B hits: ICC2,1: 0.73, SEM: 8.57). Motor RT (ICC2,1: 0.63, SEM: 0.035s) showed fair reliability, while average RT per hit for Modes A and B showed moderate reliability (ICC2,1: 0.68, SEM: 0.43 s and ICC2,1: 0.72, SEM: 0.03 s respectively). It appears that one familiarization trial is necessary for the choice reaction time (CRT) task while three familiarization trials are necessary for reactive RT tasks. In conclusion, results indicate that the Dynavision™ D2 is a reliable device to assess neuromuscular reactivity given that an adequate practice is provided. The data presented are generalizable to a population of recreationally active young adults. Key PointsThe Dynavision™ D2 is a light-training reaction device, developed to train sensory motor integration through the visual system, offering the ability to assess visual and motor reaction to both central and peripheral stimuli, with a capacity to integrate increasing levels of cognitive challenge.The Dynavision™ D2 is a reliable instrument for assessing reaction time in recreationally active young adults.It is recommended that one familiarization trial is necessary for the choice reaction time task assessment to learn the test protocol, while three familiarization trials are needed for reactive ability in Mode A and Mode B before a subsequent reliable baseline score can be established.Significant training effects were observed for all reaction time tests and should be taken into account with continuous trials.
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This study compared performance and muscle architecture (MA) changes in starters (S) and nonstarters (NS) during a National Collegiate Athletic Association Division I women's soccer season. Twenty-eight women (19.9 ± 1.1 years; 1.71 ± 0.08 m; 64.7 ± 6.4 kg) were monitored for vertical jump power (VJP), repeated line drills (LDs), 3-dimensional multiple object tracking (3D-MOT), and reaction time (RT) at preseason, midseason, and postseason. Muscle architecture changes using ultrasonography were assessed at preseason and postseason. Comparisons between S (n = 11; 70.0 ± 14.6 min per game) and NS (n = 17; 8.4 ± 8.0 min per game) were performed to make magnitude-based inferences. No differences were seen in VJP during the season in either group. Starters were more likely (81.1%) to decrease LD time than NS, with no differences in fatigue rate. Starters and NS improved 3D-MOT (1.14 ± 0.41 to 1.55 ± 0.43) and RT (0.37 ± 0.05 to 0.34 ± 0.33 seconds), with no differences between groups. Rectus femoris (RF) echo intensity improved (65.57 ± 1.50 to 61.26 ± 1.59) in both groups, with no interactions observed. Cross-sectional area (20.84 ± 3.58 to 21.46 ± 3.66 cm) increased and pennation angle (PANG) (12.58 ± 2.56 to 11.78 ± 2.03°) decreased for both groups in the vastus lateralis (VL). Muscle architecture comparisons between groups revealed S likely decreased VL muscle thickness (MT) and PANG (81.6 and 79.4%, respectively) and possibly decreased RF MT and PANG (65.7 and 59.4%, respectively) when compared with NS. Results indicate that VJP and LD fatigue rate are not changed during a competitive season, but S become faster than NS. Three-dimensional multiple object tracking and RT improve regardless of playing time. Changes in MA indicate that practices alone provide sufficient stimulus for improving muscle quality during the competitive season.
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Rendimiento Atlético/fisiología , Músculo Esquelético/anatomía & histología , Fútbol/fisiología , Rendimiento Atlético/estadística & datos numéricos , Femenino , Humanos , Fuerza Muscular/fisiología , Músculo Esquelético/fisiología , Aptitud Física/fisiología , Tiempo de Reacción/fisiología , Entrenamiento de Fuerza , Fútbol/estadística & datos numéricos , Estados Unidos , Universidades , Adulto JovenRESUMEN
A curved treadmill offers a practical method of assessing anaerobic power by enabling unrestricted running motion and greater sport specificity. The purpose of this research was to determine reliability of a curved treadmill (cTM) sprint test and to compare performance measures to the traditional Wingate anaerobic power test (WAnT) performed on a cycle ergometer. Thirty-two recreationally active men and women (22.4 ± 2.8 yrs; 1.73 ± 0.08 m; 74. 2 ± 13.2 kg) performed four familiarization trials on cTM, followed by two randomly assigned experimental trials consisting of one 30-second maximum effort on either cTM or WAnT. Each trial was separated by at least 48 hours. Repeated measures analysis of variance (ANOVA), interclass correlations (ICC), standard error of measurement (SEM), and minimal differences (MD) were used to determine reliability of familiarization trials on cTM, and Pearson product moment correlations were calculated to compare cTM and WAnT. ANOVA results showed significant differences (p < 0.05) during the four familiarization trials. Post hoc analysis showed significant differences (p < 0. 05) between the first two trials. Familiarization trials 3 and 4 showed a high reliability for each performance variable (distance: ICC2,1 = 0.969, %SEM = 2.645, p = 0.157; mean velocity: ICC2,1 = 0. 969, %SEM = 2.622, p = 0.173; peak velocity: ICC2,1 = 0.966, %SEM = 3.142, p = 0.033; mean power: ICC2,1 = 0.940, %SEM = 4.140, p = 0.093; and peak power: ICC2,1 = 0.887, %SEM = 11.244, p = 0.669). Participants elicited an average peak power of 1050.4 ± 338.5 Watts on cTM and 1031.4 ± 349.8 Watts on WAnT. Pearson product moment coefficients indicated high correlations between peak power, mean power, and peak velocity (r = 0.75, p < 0.001; r = 0.84, p < 0.001; and r = 0.76, p < 0. 001, respectively) derived from cTM and WAnT. In conclusion, results suggest that after two familiarization trials, cTM is a reliable sprint test for recreationally active men and women. In addition, there are strong relationships between cTM and WAnT in assessing anaerobic performance. Key pointsThe Woodway Curve 3.0(TM) is a non-motorized treadmill utilizing a curved platform which allows individuals to simulate an unrestricted sprint test in a laboratory setting, offering a practical and sport specific method of assessing anaerobic power.The curved treadmill provides a reliable sprint test for recreationally active men and women.There are strong relationships between the curved treadmill and cycle ergometer in assessing anaerobic performance.
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Participation in sports, especially those involving impact loading, enhance bone mineral content (BMC) and density (BMD). Additionally, participation in impact loading sports may strengthen relationships between strength or power and bone variables. The purpose of this investigation was to examine relationships between measures of muscular performance and bone variables in Division I endurance athletes (29 males, 31 females, 19.6 ± 1.4 years). Dual-energy x-ray absorptiometry (DXA) scans were analyzed at the anterior-posterior (AP) and lateral (LAT) spine, femoral neck (FN), total hip (TH), whole body (WB), and ultra-distal forearm (UD) for BMC and BMD measures. WB scans provided information for bone-free lean mass (BFLM). Performance measures included absolute, and relative (to body weight), grip strength (GS) and absolute lower body power (LBP) derived from a vertical jump. Pearson correlation coefficients were determined between bone variables and muscular performance measures. Hierarchical multiple regression was used to quantify the variance explained in bone variables. Male runners showed strong relationships between absolute and relative GS and numerous bone variables. Female runner had significant relationships between absolute jump power and numerous bone variables. Sex, GS, and LBP explained 41-76% of BMC at the various bone sites and 12-30% of BMD. Results indicate that in collegiate men, greater strength is related to higher BMC and BMD, however this was not the case for women. In female collegiate distance runners, higher jump power was related to greater BMC and BMD.
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BACKGROUND: A dietary supplement containing a blend of 170 mg of N-oleyl-phosphatidylethanolamine (NOPE) and 100 mg of epigallocatechin-3-gallate (EGCG) has been shown to improve compliance to low caloric diets. Considering the cost of dietary ingredients, many manufacturers attempt to determine the lowest efficacious dose. Thus, the purpose of this study was to evaluate the efficacy of 8-weeks of supplementation with a daily intake of 120 mg of NOPE and 105 mg of EGCG in conjunction with a low caloric diet and regular, moderate exercise on dietary compliance in healthy, overweight adults. An additional purpose was to examine the effect of this supplement/diet/exercise paradigm on changes in body composition, sensation of appetite, mood and severity of binge eating. METHODS: Fifty healthy, overweight (BMI > 25 m·kg²) men (15) and women (35) (SUP; n = 25; 32.7 ± 13.75 y; BMI = 33.4 ± 6.2; PLA; n = 25, 34.3 ± 12.7 years; BMI = 33.2 ± 6.8) were recruited for a double-blind, placebo controlled study. Each volunteer was randomly assigned to either the supplement (SUP; n = 25) or placebo group (PLA; n = 25). Based upon a self-reported 3-day dietary recall all volunteers were recommended a 500 kcal or 30% (maximum of 1000 kcal) reduction in caloric intake. Volunteers were also encouraged to exercise 30 minutes per day, three times per week. RESULTS: Subjects in SUP were significantly more compliant (x² = 3.86, p = 0.049) in maintaining a low caloric diet at week 4, but this was not able to be maintained through the 8-week study. In addition, a significant difference in mood, feelings of fatigue and confusion were noted between the groups at week 4, but again not maintained by week 8 where only feelings of tension were improved. No differences between groups (p > 0.05) were observed for body mass, body composition, feelings of hunger, and binge eating after eight weeks. CONCLUSION: Supplementing with a combination of 120 mg of NOPE and 105 mg of EGCG does appear to enhance compliance to a low caloric diet and improve mood for 4 -weeks, but loses its effectiveness by week 8.
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Catequina/análogos & derivados , Suplementos Dietéticos , Sobrepeso/dietoterapia , Fosfatidiletanolaminas/administración & dosificación , Tejido Adiposo/patología , Adulto , Afecto , Fármacos Antiobesidad/administración & dosificación , Catequina/administración & dosificación , Dieta Reductora , Método Doble Ciego , Femenino , Humanos , Masculino , Persona de Mediana Edad , Sobrepeso/patología , Sobrepeso/psicología , Cooperación del Paciente/psicología , Factores de Tiempo , Resultado del Tratamiento , Adulto JovenRESUMEN
Modification of bone is continuous throughout life and influenced by many factors, including physical activity. This study investigated changes in areal bone mineral density (aBMD) and hip structure among male and female collegiate distance runners and non-athlete controls over 12 months. Using dual-energy x-ray absorptiometry (DXA) and hip structure analysis (HSA) software, aBMD at the posterior-anterior (PA) and lateral spine, femoral neck, total hip (TH), whole body (WB), and bone geometry at the narrow neck (NN) of the femur was measured three times over 12 months. HSA included cross-sectional area (CSA), cross-sectional moment of inertia (CSMI), and Z-section modulus (Z). Male runners had significantly higher aBMD at TH and WB and greater CSA, CSMI, and Z than male controls at the end of 12 months. Female controls had higher aBMD at the PA spine than female runners at the end of 12 months. Male runners had significant increases in aBMD at the PA (p = 0.003) and lateral spine (p = 0.002), and TH (p = 0.002), female runners had significant decreases in aBMD at TH (p = 0.015) and WB (p = 0.002), male controls had significant increases in aBMD at the PA spine (p < 0.001) and WB (p < 0.001), and female controls had significant decreases in aBMD at lateral spine and TH (p = 0.008) over the year. When applying covariates of bone-free lean mass and vitamin D, male distance runners demonstrated significant improvement in CSA (3.602 ± 0.139 vs. 3.675 ± 0.122 cm2, p = 0.05), CSMI (3.324 ± 0.200 to 3.467 ± 0.212 cm4, p < 0.05), and Z (1.81 ± 0.08 to 1.87 ± 0.08 cm3, p = 0.05) during the study. No other changes in hip structure occurred over the year. Distance running may be beneficial to aBMD and hip structure in college-age males but not females. Further research is needed on potential influences of weight-bearing activity, energy availability, and hormonal status on aBMD and hip structure in males and females.
RESUMEN
A number of factors determine neuromuscular economy (NE) and running economy (RE) in endurance-trained runners. The purpose of this investigation was to examine the relationship between aerobic fitness and NE in endurance-trained runners. Twenty-seven endurance-trained runners (25.1⯱â¯10.2â¯y) completed a maximal voluntary isometric contraction of the leg extensors to measure maximal electromyography (EMGmax) amplitude of the vastus lateralis (VL) and rectus femoris (RF), a steady-state treadmill run at 9.66, 11.27, and 12.87â¯kmâhr-1 and a maximal graded exercise test. Participants were outfitted with surface electrodes over the VL and RF muscles to record EMG amplitude throughout each test. During the steady-state test, the EMG (as a percentage of EMGmax) and oxygen consumption (VO2) over the final minute of each stage were established and considered NE and RE, respectively. Pearson product moment correlations were used to determine the relationships between VO2max and velocity at VO2max (vVO2max) and NE and RE. The results revealed significant negative correlations between VO2max and vVO2max and relative NE and RE at all three speeds. In addition, there were significant correlations between relative RE and NE at all three speeds. These results indicate that faster runners have improved NE and RE when expressed as a relative measure.
Asunto(s)
Atletas , Capacidad Cardiovascular , Entrenamiento Aeróbico , Músculo Cuádriceps/fisiología , Carrera/fisiología , Adolescente , Adulto , Electromiografía , Prueba de Esfuerzo , Femenino , Humanos , Contracción Isométrica , Masculino , Consumo de Oxígeno , Resistencia Física , Adulto JovenRESUMEN
The purpose of this study was to examine the effect of the L-Alanyl-L-Glutamine dipeptide (AG) on cognitive function and reaction time (RT) following endurance exercise. Twelve male endurance athletes (23.5 ± 3.7 y; 175.5 ± 5.4 cm; 70.7 ± 7.6 kg) performed four trials, each consisting of running on a treadmill at 70% of VO2max for 1h, then at 90% of VO2max until exhaustion. One trial consisted of no hydration (DHY), another required ingestion of only a sports electrolyte drink (ED) and two trials required ingestion of a low dose (LD; 300 mg·500 ml(-1)) and high dose (HD) of AG (1 g·500ml(-1)) added to the ED. Cognitive function and reaction tests were administered pre- and post-exercise. Magnitude based inferences were used to analyze ∆ cognitive function and ∆ reaction test data. Results indicated that DHY had a possible negative effect on number of hits in a 60-sec reaction test compared to LD and HD, while ED appeared to have a negative effect compared to HD. Analysis of lower body quickness indicated that LD and HD were likely improved in comparison to DHY. Performance on the serial subtraction test appeared to be possibly better in ED than DHY, while other comparisons between groups regarding cognitive function were unclear. In conclusion, rehydrating with AG during submaximal exercise may maintain or enhance subsequent RT in upper and lower body activities compared to DHY. These same effects were not apparent when participants consumed ED.
Asunto(s)
Cognición/efectos de los fármacos , Dipéptidos/farmacología , Resistencia Física/fisiología , Tiempo de Reacción/efectos de los fármacos , Adulto , Bebidas , Deshidratación , Suplementos Dietéticos , Ejercicio Físico , Humanos , Masculino , Adulto JovenRESUMEN
The effect of altitude on soccer game activity profiles was retrospectively examined in six NCAA Division I female soccer players. Comparisons were made between two matches played at sea level (SL) and one match played at a moderate altitude (1839 m). A 10-Hz global positioning system device was used to measure distance and velocity. The rate of total distance capacity (TDC) and high intensity running (HIR) as well as percent of time at HIR were evaluated. Significant differences were seen in the distance rate (120.55 ± 8.26 m·min-1 versus 105.77 ± 10.19 m·min-1) and the HIR rate (27.65 ± 9.25 m·min-1 versus 25.07 ± 7.66 m·min-1) between SL and altitude, respectively. The percent of time at HIR was not significantly different (p = 0.064), yet tended to be greater at SL (10.4 ± 3.3%) than at altitude (9.1 ± 2.2%). Results indicate that teams residing at SL and competing at a moderate altitude may have a reduced ability in distance covered and a high intensity run rate.
RESUMEN
PURPOSE: During the competitive soccer season, women's intercollegiate matches are typically played on Friday evenings and Sunday afternoons. The efficacy of a 42-h recovery period is not well understood. This investigation was conducted to determine performance differences between Friday and Sunday matches during a competitive season. METHODS: Ten NCAA Division I female soccer players (20.5±1.0 y, 166.6±5.1 cm, 61.1±5.8 kg) were monitored with 10-Hz GPS devices across 8 weekends with matches played on Friday evenings and Sunday afternoons. The players were outside backs, midfielders, and forwards. All players had to participate in a minimum of 45 min/match to be included in the study. Average minutes played, total distance covered, total distance of high-intensity running (HIR) (defined as running at a velocity equal to or exceeding 3.61 m/s for longer than 1 s), the number of HIR efforts, and the number of sprints were calculated for each match. Data for Friday vs Sunday matches were averaged and then compared using dependent t tests. RESULTS: No differences were seen in minutes played, distance rate, or number of sprints between Friday and Sunday matches. A significant (P=.017) decrease in rate of HIR between Friday (25.37±7.22 m/min) and Sunday matches (22.90±5.70 m/min) was seen. In addition, there was a trend toward a difference (P=.073) in the number of efforts of HIR between Friday (138.41±36.43) and Sunday (126.92±31.31). CONCLUSIONS: NCAA Division I female soccer players cover less distance of HIR in games played less than 48 h after another game. This could be due to various factors such as dehydration, glycogen depletion, or muscle damage.
Asunto(s)
Rendimiento Atlético , Resistencia Física/fisiología , Carrera/fisiología , Fútbol/fisiología , Femenino , Humanos , Análisis y Desempeño de Tareas , Factores de Tiempo , Adulto JovenRESUMEN
BACKGROUND: There are no known studies that have examined ß-alanine supplementation in military personnel. Considering the physiological and potential neurological effects that have been reported during sustained military operations, it appears that ß-alanine supplementation may have a potential benefit in maintaining physical and cognitive performance during high-intensity military activity under stressful conditions. The purpose of this study was to examine the effect of 28 days of ß-alanine ingestion in military personnel while fatigued on physical and cognitive performance. METHODS: Twenty soldiers (20.1 ± 0.9 years) from an elite combat unit were randomly assigned to either a ß-alanine (BA) or placebo (PL) group. Soldiers were involved in advanced military training, including combat skill development, navigational training, self-defense/hand-to-hand combat and conditioning. All participants performed a 4-km run, 5-countermovement jumps using a linear position transducer, 120-m sprint, a 10-shot shooting protocol with assault rifle, including overcoming a misfire, and a 2-min serial subtraction test to assess cognitive function before (Pre) and after (Post) 28 days of supplementation. RESULTS: The training routine resulted in significant increases in 4-km run time for both groups, but no between group differences were seen (p = 0.597). Peak jump power at Post was greater for BA than PL (p = 0.034), while mean jump power for BA at Post was 10.2% greater (p = 0.139) than PL. BA had a significantly greater (p = 0.012) number of shots on target at Post (8.2 ± 1.0) than PL (6.5 ± 2.1), and their target engagement speed at Post was also significantly faster (p = 0.039). No difference in serial subtraction performance was seen between the groups (p = 0.844). CONCLUSION: Results of this study indicate that 4-weeks of ß-alanine ingestion in young, healthy soldiers did not impact cognitive performance, but did enhance power performance, marksmanship and target engagement speed from pre-ingestion levels.