The Impact of an 8-Week Resisted Sprint Training Program on Ice Skating Performance in Male Youth Ice Hockey Players.

ABSTRACT: Dietze-Hermosa, MS, Montalvo, S, Gonzalez, MP, and Dorgo, S. The impact of an 8-week, resisted, sprint training program on ice skating performance in male youth ice hockey players. J Strength Cond Res 38(5): 957-965, 2024-The purposes of this randomized control study were to (a) compare the effects of an on-ice versus an overground resisted sprint training intervention and a control condition and (b) identify changes in ice skating kinematics and kinetics after training intervention participation. Twenty-four youth ice hockey players were randomly allocated into 3 groups: (a) on-ice resisted sprint training (on-ice RST); (b) overground resisted sprint training (overground RST); and (c) body weight resistance training (control). During the 8-week intervention, the 2 RST groups engaged in sled towing methods, whereas the control group engaged in a body weight resistance training program twice a week. A series of individual, repeated-measures analysis of variances with post hoc pairwise comparisons were conducted for variables of interest. An interaction effect was noted for ice skating s-cornering agility drill completion time ( p = 0.01; ηp2 = 0.36), ice skating 30-m top speed completion time ( p = 0.04; ηp2 = 0.27), step length ( p = 0.04; ηp2 = 0.26), and knee angle at touchdown ( p = 0.03; ηp2 = 0.30). The on-ice RST group displayed superior improvements across ice skating tests compared with the control group. Data show that on-ice RST has the greatest transfer effect to ice skating metrics; however, improvements in certain ice skating metrics can be observed with overground training also.

Should ECG criteria for Low QRS voltage (LQRSV) be specific for Sex?

INTRODUCTION: Low QRS peak-to-nadir voltage (LQRSV) is associated with arrhythmogenic right ventricular cardiomyopathy (ARVC) and other cardiomyopathies. Recent studies have proposed criteria for LQRSV when screening athletes for cardiovascular disease. These criteria have not yet been evaluated in a large population of healthy young athletes. METHODS: The target population was 10,728 (42.5% female, 57.5% male, mean age 18.1 ± 4.3 years) athletes who participated in mass ECG screenings between 2014 and 2021 at multiple sites across the United States including grade schools (11%), high schools (32%), colleges (50%), and professional athletic teams (6%) with digitally recorded ECGs and a standardized protocol. Since by design, complete follow up for outcomes and the results of testing were not available. Including only ECGs from initial evaluation among athletes 14-35 years of age and excluding those with right bundle branch block, left bundle branch block, Wolf-Parkinson-White pattern, reversed leads and 3 clinically diagnosed cardiomyopathies at Stanford, 8,679 (58% males, 42% females) remained eligible for analysis. QRS voltage was analyzed for each ECG lead and LQRSV criteria were applied and stratified by sex. RESULTS: QRS voltage was lower in all leads in female athletes compared to male athletes. Using traditional limb lead criteria or precordial lead criteria, the prevalence of LQRSV was significantly lower in males than females (P < .001). Strikingly, LQRSV using the Sokolow-Lyon Index was present in 1.9% of males and 9.8% of females (P < .001). Applying first percentile for LQRS amplitude criteria provided possible values for screening young athletes for LQRSV. CONCLUSIONS: LQRSV is more common among female athletes than male athletes using established criteria. Using first percentile sex-specific cut points should be considered in future analyses. Proposed novel LQRSV criteria in young athletes should be specific for males and females.

Digitized Electrocardiography Measurements Support the Biological Plausibility of the Pathological Significance of ST Segments in Athletes.

OBJECTIVE: ST segment deviations around the isoelectric line are common findings in manifest cardiovascular disease. In athletes, ST elevation is common, while ST depression is considered rare. However, clinical studies in athletes have associated ST depression with myocardial fibrosis and fatty infiltration and ST elevation with pericarditis and myocarditis. This study aims to explore the association between resting ST segment deviations and resting heart rate, an indicator of training and autonomic tone and electrocardiography (ECG) markers of exercise training effect and cardiovascular health R and T wave amplitude. DESIGN: Retrospective analysis of digitized ECG data. SETTING: Institutional setting. PARTICIPANTS: Seven thousand eight hundred thirty-six (male athletes = 4592, female athletes = 3244) healthy asymptomatic athletes (14-35 years). MAIN OUTCOME MEASURES: A series of correlations and regressions were conducted between ST depression (<0.0 µV) and ST elevation (>0.0 µV), on R and T wave amplitudes, and heart rate in leads V2, V5, and aVF. RESULTS: Positive correlations between ST elevation and R and T wave (S wave in V2) amplitudes and leads V5, V2, and aVF in male and female athletes (range of r = 0.1-0.54). In addition, there was a negative correlation between ST elevation and HR for male and female athletes. Finally, there was a negative correlation between ST depression and R wave and HR for male and female athletes in V5 (P < 0.01). CONCLUSIONS: In athletes, ST segment elevation is correlated with R and T wave amplitudes and negatively correlated with HR. In addition, ST segment elevation is correlated with low heart rate, consistent with its higher prevalence in athletes. ST segment depression is not influenced by HR but is negatively associated with R and T wave amplitudes.

Assessing the Assisted Six-Minute Cycling Test as a Measure of Endurance in Non-Ambulatory Patients with Spinal Muscular Atrophy (SMA).

Assessing endurance in non-ambulatory individuals with Spinal Muscular Atrophy (SMA) has been challenging due to limited evaluation tools. The Assisted 6-Minute Cycling Test (A6MCT) is an upper limb ergometer assessment used in other neurologic disorders to measure endurance. To study the performance of the A6MCT in the non-ambulatory SMA population, prospective data was collected on 38 individuals with SMA (13 sitters; 25 non-sitters), aged 5 to 74 years (mean = 30.3; SD = 14.1). The clinical measures used were A6MCT, Revised Upper Limb Module (RULM), Adapted Test of Neuromuscular Disorders (ATEND), and Egen Klassifikation Scale 2 (EK2). Perceived fatigue was assessed using the Fatigue Severity Scale (FSS), and effort was assessed using the Rate of Perceived Exertion (RPE). Data were analyzed for: (1) Feasibility, (2) Clinical discrimination, and (3) Associations between A6MCT with clinical characteristics and outcomes. Results showed the A6MCT was feasible for 95% of the tested subjects, discriminated between functional groups (p = 0.0086), and was significantly associated with results obtained from RULM, ATEND, EK2, and Brooke (p < 0.0001; p = 0.029; p < 0.001; p = 0.005). These findings indicate the A6MCT's potential to evaluate muscular endurance in non-ambulatory SMA individuals, complementing clinician-rated assessments. Nevertheless, further validation with a larger dataset is needed for broader application.

Effects of manual resistance versus weight resistance training on body composition and strength in young adults after a 14-week intervention.

Manual Resistance Training (MRT) is an alternative training modality where the external resistance is provided by a spotter. PURPOSE: The purpose of this study was to observe changes in body composition and muscular fitness after a 14-week MRT intervention compared to changes elicited by a Weight Resistance Training (WRT) intervention. METHODS: Eighty-four young adults were randomly assigned to either the MRT (n = 53, height 170.1 ± 8.1 cm, body mass 73.9 ± 16.0 kg, and body fat 24.6 ± 8.7%) or WRT (n = 31, mean ± SD: height 169.6 ± 10.1 cm, body mass 75.0 ± 17.4 kg, and body fat 24.7 ± 8.5%) group. Body composition was assessed by Dual-energy X-ray Absorptiometry (DEXA), muscular strength and muscular endurance were tested before and after the intervention. RESULTS: Findings indicated that trunk, arm, leg, and total lean mass increased in both groups after the intervention (p < 0.05). Moreover, total fat mass significantly decreased compared to baseline in both groups (p < 0.05). However, no statistically significant changes were observed in Bone Mineral Density and Bone Mineral Content in response to the intervention. Both MRT and WRT programs were successful at significantly increasing muscular strength and endurance (p < 0.05). CONCLUSION: The changes in body composition after a 14-week MRT program were similar to those of the WRT intervention. Hence, an MRT program may be effectively used to increase lean mass and decrease fat mass.

Commercial Smart Watches and Heart Rate Monitors: A Concurrent Validity Analysis.

ABSTRACT: Montalvo, S, Martinez, A, Arias, S, Lozano, A, Gonzalez, MP, Dietze-Hermosa, MS, Boyea, BL, and Dorgo, S. Smartwatches and commercial heart rate monitors: a concurrent validity analysis. J Strength Cond Res 37(9): 1802-1808, 2023-The purpose of this study was to explore the concurrent validity of 2 commercial smartwatches (Apple Watch Series 6 and 7) against a clinical criterion device (12-lead electrocardiogram [ECG]) and a field criterion device (Polar H-10) during exercise. Twenty-four male collegiate football players and 20 recreationally active young adults (10 men and 10 women) were recruited and participated in a treadmill-based exercise session. The testing protocol included 3 minutes of standing still (resting), then walking at low intensity, jogging at a moderate intensity, running at a high intensity, and postexercise recovery. The intraclass correlation (ICC 2,k ), and Bland-Altman plot analyses showed a good validity of the Apple Watch Series 6 and Series 7 with increased error (bias) as jogging and running speed increased in the football and recreational athletes. The Apple Watch Series 6 and 7 are highly valid smartwatches at rest and different exercise intensities, with validity decreasing with increased running speed. Strength and conditioning professionals and athletes can confidently use the Apple Watch Series 6 and 7 when tracking heart rate; however, caution must be taken when running at moderate or higher speeds. The Polar H-10 can surrogate a clinical ECG for practical applications.

A Comparison of Morphological, Jump, and Sprint Kinematic Asymmetries in Division I Track and Field Athletes.

Inter-limb asymmetries are the difference in performance in one limb with respect to the other. Running events in track and field are considered symmetrical while jumping and throwing events are considered asymmetrical. It is unknown if competing in these different events result in differences in inter-limb asymmetries, thus, this study compared the magnitude of jump, sprint, and morphological asymmetries in track and field athletes who compete in symmetrical and asymmetrical events. Forty-six Division I track and field athletes performed a series of vertical jumps (VJ) and broad jumps (BJ) with force platforms measuring peak force of each limb, and 30-meter fly sprints with kinematics (step length (SL), flight time (FT), and contact time (CT)) recorded during the sprints. Additionally, thirty-eight of these subjects underwent body composition analysis via dual x-ray absorptiometry to determine morphological asymmetries. Asymmetries were calculated using the symmetry index and the asymmetry measures were compared between sprinters, distance runners, throwers, and jumpers utilizing a one-way analysis of variance or Kruskal-Wallis tests with post-hoc comparisons as necessary. There were no differences in VJ, BJ, and sprint kinematic asymmetries found between groups but there were differences in leg fat mass asymmetries (H(3)=8.259, p=0.041, eta2= 0.101) as well as arm lean mass (H(3)=9.404, p=0.024, eta2=0.152), fat mass (H(3)=17.822, p<0.001, eta2=0.353), and tissue mass (H(3)=11.632, p=0.009, eta2=0.206) asymmetry measures. While morphological asymmetry differences may be present in athletes competing in different events, there does not appear to be differences in asymmetries during the VJ, BJ, and 30-m fly sprint.

Near Infrared Spectroscopy is not a Surrogate of Venous Occlusion Plethysmography to Assess Microvascular Resting Blood Flow and Function.

Near-infrared spectroscopy (NIRS) is a non-invasive technique that measures tissue perfusion using red blood cells oxygen saturation and venous occlusion plethysmography (VOP) is the gold standard to assess microvascular blood flow and function. The purpose of this study was to determine if NIRS can surrogate the microvascular blood flow assessment after an ischemic challenge obtained via VOP. Twenty apparently healthy subjects (10 males and 10 females), aged 18 to 35 years, were recruited for this single session study. NIRS probes were placed 40mm apart along the epicondylar muscles on the right forearm and on the tibialis anterior on the right lower leg, while VOP strain gauges were placed on the largest circumference on both right forearm and calf. Blood flow via VOP and NIRS variables (hemoglobin saturation (SO2), oxygenated hemoglobin (HbO2), and deoxyhemoglobin (HHb) slopes) were assessed before and after 5-min ischemic challenge. Person's correlations and intra-class correlations (ICC2k) were conducted for each of the NIRS variables vs VOP. There were moderate associations between of SO2 and HbO2 slopes and VOP (r = 0.59, p < 0.01 and r = 0.53, p < 0.05, respectively) at the lower body during resting conditions. There was a poor agreement between NIRS SO2 and VOP at the resting condition in the lower body (ICC2k = 0.45). There were no other associations between any of the other NIRS variables and VOP of the lower and upper body at resting or post-ischemic conditions. In conclusion, NIRS cannot surrogate VOP for measurements of microvascular blood flow at resting or post-ischemic conditions.

Differences in Blood Flow Patterns and Endothelial Shear Stress at the Carotid Artery Using Different Exercise Modalities and Intensities.

Endothelial dysfunction is the first pathophysiological step of atherosclerosis, which is responsible for 90% of strokes. Exercise programs aim to reduce the risk of developing stroke; however, the majority of the beneficial factors of exercise are still unknown. Endothelial shear stress (ESS) is associated with endothelial homeostasis. Unfortunately, ESS has not been characterized during different exercise modalities and intensities in the carotid artery. Therefore, the purpose of this study was to determine exercise-induced blood flow patterns in the carotid artery. Fourteen apparently healthy young adults (males = 7, females = 7) were recruited for this repeated measures study design. Participants completed maximal oxygen consumption (VO2max) tests on a Treadmill, Cycle-ergometer, and Arm-ergometer, and 1-repetition maximum (1RM) tests of the Squat, Bench Press (Bench), and Biceps Curl (Biceps) on separate days. Thereafter, participants performed each exercise at 3 different exercise intensities (low, moderate, high) while a real-time ultrasound image and blood flow of the carotid artery was obtained. Blood flow patterns were assessed by estimating ESS via Womersley's estimation and turbulence via Reynold's number (Re). Data were analyzed using a linear mixed-effects model. Pairwise comparisons with Holm-Bonferroni correction were conducted with Hedge's g effect size to determine the magnitude of the difference. There was a main effect of intensity, exercise modality, and intensity * exercise modality interaction on both ESS (p < 0.001). Treadmill at a high intensity yielded the greatest ESS when compared to the other exercise modalities and intensities, while Bench Press and Biceps curls yielded the least ESS. All exercise intensities across all modalities resulted in turbulent blood flow. Clinicians must take into consideration how different exercise modalities and intensities affect ESS and Re of the carotid artery.

Association and Predictive Ability of Jump Performance with Sprint Profile of Collegiate Track and Field Athletes.

This study examined the relationship between broad jump (BJ), countermovement jump (CMJ) and light load countermovement jump (LL-CMJ) performance and sprint performance and Sprint Profile measures in athletes. Additionally, this study aimed to determine the predictive ability of jump measures on Sprint Profile components. Twenty-five athletes performed BJ, CMJ, LL-CMJ, 30-metre acceleration and 30-metre maximal speed fly-by sprints. Results revealed moderate to very large correlations between BJ, CMJ and LL-CMJ performance with acceleration sprint completion times (r = -0.423 to -0.807; p < 0.05), fly-by sprint completion times (r = -0.452 to -0.838; p < 0.05) and maximal sprint speed (r = 0.424 to 0.794; p < 0.05). Additionally, associations were observed with multiple jumping measures and components of the Sprint Profile (r = 0.431 to 0.777; p < 0.05) during acceleration sprints. Furthermore, the BJ distance was the best predictor of Sprint Profile components during acceleration sprints (R2 = 0.57-0.76; p < 0.01) and maximal speed fly-by sprints (R2 = 0.775; p < 0.001). The forces and the manner of force application during the BJ to propel the athlete forwards and upwards are similar to those necessary to exhibit superior sprint performance. This may be due to the rapid generation of forces and orientation of force application during both movements.

Effects of Augmented Eccentric Load Bench Press Training on One Repetition Maximum Performance and Electromyographic Activity in Trained Powerlifters.

ABSTRACT: Montalvo, S, Gruber, LD, Gonzalez, MP, Dietze-Hermosa, MS, and Dorgo, S. Effects of augmented eccentric load bench press training on one repetition maximum performance and electromyographic activity in trained powerlifters. J Strength Cond Res 35(6): 1512-1519, 2021-Augmented eccentric load (AEL) training has been shown to elicit greater lower-body muscular strength increases and faster performance improvements compared with traditional strength training. However, it is unknown whether AEL training could provide similar improvements in upper-body muscular strength. Therefore, this study investigated the effects of a 4-week AEL training program on bench press one repetition maximum (1RM) strength, bar kinetics and kinematics, and surface electromyography (EMG) activity. Eight competitive powerlifters completed 5 training sessions consisting of 7 sets of a single repetition with up to 5 minutes rest between sets. Each session was completed at a predetermined AEL percentage consisting of 90% 1RM for concentric and supramaximal loads ranging from 105 to 125% 1RM during the eccentric phase with the use of eccentric hooks. After 4 weeks of AEL training, 1RM performance significantly increased from pretest to posttest (116.62 ± 27.48-124.28 ± 26.96 kg, p = 0.001). In addition, EMG amplitude of the pectoralis major decreased during the 125% AEL session to 59.86 ± 15.36% of pretest 1RM EMG values (p = 0.049, effect sizes [ESs] = 0.69). Furthermore, peak power of 1RM increased by 36.67% from pretest to posttest (p = 0.036, ES = 0.58). These study findings suggest that incorporating AEL bench press training into a 4-week training cycle may be a novel strategy to improve 1RM performance in competitive powerlifters in a short period.

Physical fitness in older adults: Is there a relationship with the modified Functional Movement Screen™?

INTRODUCTION: The modified Functional Movement Screen™ (mFMS) has been used to screen for mobility, stability, motor control, and balance in older adults, yet, its relationship to measures of physical fitness is not fully understood. The purpose of this study was to determine the association between mFMS scores and measures of physical fitness in older adults. A secondary aim was to determine physical fitness differences depending on mFMS Lower Body Motor Control Screen scores. METHODS: One hundred and eight older adults completed this cross-sectional study. Measurements of physical fitness included: Handgrip Strength (HG), Back-Leg Strength Dynamometer (BLS), 8 foot Up and Go (8UG), Vertical Jump (VJ), Medicine Ball Throw (MBT), Chair Stand (CST), Arm Curl (AC), and 6-Minute Walk test (6 MW). The mFMS consisted of four screens: Shoulder Mobility Screen (SMS), Deep Squat (DS), Active Straight Leg Raise (ASLR), and a Lower Body Motor Control Screen (LB-MCS). Spearman's R correlations determined associations between physical fitness tests and mFMS scores (DS, SMS, ASLR). Independent t-tests or Mann Whitney U tests determined whether individuals who passed the LB-MCS displayed higher physical fitness scores. RESULTS: The DS was significantly correlated with all fitness measures (p < 0.05). Higher DS scores were associated with better HG (r = 0.31), BLS (r = 0.49), VJ height (r = 0.54), MBT (r = 0.41), CST (r = 0.57), AC (r = 0.30), 6 MW (r = 0.50), and 8UG (r = -0.61) performance. Individuals who passed the LB-MCS displayed superior BLS, 8UG test, and 6 MW test performance (p < 0.05). DISCUSSION & CONCLUSION: Higher DS scores are associated with higher physical fitness scores. Individuals who passed the LB-MCS displayed better physical fitness scores. Practitioners may desire to use the mFMS to measure physical fitness in older adults.

Common Vertical Jump and Reactive Strength Index Measuring Devices: A Validity and Reliability Analysis.

ABSTRACT: Montalvo, S, Gonzalez, MP, Dietze-Hermosa, M, Eggleston, JD, and Dorgo, S. Common vertical jump and reactive strength index measuring devices: A validity and reliability analysis. J Strength Cond Res 35(5): 1234-1243, 2021-Several field-test devices exist to assess vertical jump, but they either lack proper validation or have been validated for the countermovement jump (CMJ) only. This study aimed to quantify the validity and reliability of metrics, including jump height and the calculated reactive strength index (RSI), obtained using the flight-time method from 4 different assessment devices with 3 different vertical jump modalities in comparison to a force platform (criterion assessment). The Optojump, Push-Band 2.0, MyJump2 mobile application, and What'sMyVert mobile application were used synchronously and together with the force platforms. Thirty subjects (17 males and 13 females; age ± SD: 23.37 ± 1.87 years) performed 5 repetitions of CMJ, squat jump (SQJ), and drop jump (DJ) with a standardized 90° knee flexion for all jumps. Relative reliability was determined by intraclass correlation (ICC) and absolute reliability by coefficient of variation (CV) analyses. Excellent reliability was considered as ICC > 0.9 and CV < 10%. Validity was obtained through an ordinary least products regression, ICC, and CV. Significance was set at p < 0.05. Reliability was excellent on jump height for the CMJ (ICC ≥ 0.98; CV ≤ 8.14%) for all instruments. With the exception of the Optojump, all instruments also had excellent reliability for the SQJ (ICC ≥ 0.98; CV ≤ 6.62) and DJ (ICC ≥ 0.94; CV ≤ 8.19). For the RSI metric, all instruments had excellent relative reliability (ICC ≥ 0.92), but none had excellent absolute reliability (CV ≥ 12.5%). The MyJump2 and What'sMyVert apps showed excellent validity on all jump modalities and RSI. The Optojump and Push-Band 2.0 devices both showed system and proportional bias for several jump modalities and RSI. Overall, both mobile applications may provide coaches with a cost-effective and reliable measurement of various vertical jumps.

Sprint Training on a Treadmill vs. Overground Results in Modality-Specific Impact on Sprint Performance but Similar Positive Improvement in Body Composition in Young Adults.

Dorgo, S, Perales, JJ, Boyle, JB, Hausselle, J, and Montalvo, S. Sprint training on a treadmill vs. overground results in modality-specific impact on sprint performance but similar positive improvement in body composition in young adults. J Strength Cond Res 34(2): 463-472, 2020-The effects of different sprint training modalities on body composition are not yet known, and the effectiveness of using motorized treadmills for sprint training is yet to be assessed accurately. The following study investigated the effects of motorized treadmill and overground training on sprint performance and body composition. Sixty-four young adults (33 men and 31 women) completed 12 sprint training sessions over a 6-week period either on a treadmill (TM) or overground (TR), or followed their normal exercise routine (CONTROL). Fifty-yard sprint time, 20-yard maximal sprint speed split time, and maximal treadmill speed were used as sprint performance indicators. Body composition and sprint performance assessments were completed before and after the 6-week intervention. On completion of the 6-week training program, maximal treadmill speed significantly increased for all 3 groups, while split sprint time significantly decreased for the TR group. The CONTROL group's 50-yd sprint time and split sprint time significantly worsened after 6 weeks. Improvements in sprint time and speed were significantly greater for the TR and TM groups compared with the CONTROL group for 50-yd sprint time, 20-yard maximal sprint speed split time, and maximal treadmill sprint speed. The change in maximal treadmill sprint speed for the TM group was significantly greater than that of the TR group. TR and TM subjects also showed significant decrease in total body fat and increase in leg lean muscle mass. These findings indicate that although overground sprint training resulted in the greatest performance improvements within overground sprint tests, sprint training on a motorized treadmill may be a beneficial alternative modality to overground sprint training and may also positively impact subjects' body composition.

The effect of different stretching protocols on vertical jump measures in college age gymnasts.

BACKGROUND: Gymnastics is a sport that requires rapid display of explosive power expressed through the vertical jump. Recent studies have shown that a static-stretching based warm-up is ineffective for explosive power development. The aim of this study was to compare different stretching protocols and their effect on vertical jump measures. METHODS: Eleven gymnasts (9 males, 2 females; 23.18±2.52 yrs) participated in this randomized crossover study. Participants were measured on the countermovement jump (CMJ), squat jump (SQJ), and depth jump (DJ) at baseline (no warm-up). Participants were then randomly placed into one of four stretching protocols: Static (ST), dynamic (DY), static + dynamic (ST+DY), and dynamic + static (DY+ST) and tested on the CMJ, SQJ, and DJ. A photoelectric cell device was used to measure vertical jump height (VJH), flight time (FT), power output (PO), and Reactive Strength Index (RSI). The non-parametric Friedman test was used to test differences between stretching protocols. RESULTS: The DY protocol showed significant improvements in VJH, FT, and PO in the CMJ. The ST, ST+DY, and DY+ST protocols did not show any significant improvements. CONCLUSIONS: A warm-up consisting of dynamic movements that resemble those used in the sport of gymnastics can improve vertical jump measures, as reflected through the CMJ.