Measuring Decrement in Change-of-Direction Speed Across Repeated Sprints in Basketball: Novel vs. Traditional Approaches.

ABSTRACT: Scanlan, AT, Madueno, MC, Guy, JH, Giamarelos, K, Spiteri, T, and Dalbo, VJ. Measuring decrement in change-of-direction speed across repeated sprints in basketball: Novel vs. traditional approaches. J Strength Cond Res 35(3): 841-845, 2021-Approaches to quantify decrement in change-of-direction speed during repeated sprints in basketball players have traditionally used total performance time, which is strongly influenced by linear speed. The purpose of this study was to compare performance decrement across change-of-direction sprints using total performance time and a novel approach that better isolates change-of-direction speed, termed change-of-direction deficit (CODD). Semiprofessional basketball players (N = 8; 19.9 ± 1.5 years; 183.0 ± 9.6 cm; 77.7 ± 16.9 kg) completed 12 × 20-m change-of-direction sprints (Agility 5-0-5 trials) with 20-second recoveries between each sprint. Agility 5-0-5 performance time was taken as the duration to cover 5 m immediately before and after (10 m in total) a 180° directional change. Change-of-direction deficit was calculated as the difference between mean 10- and 20-m split time determined during reference 20-m linear sprints in a separate session and Agility 5-0-5 time in each sprint. Performance decrement was calculated for each approach as: ([total time/ideal time] × 100) - 100. Comparisons between approaches were made using a paired-sample t-test, effect size analyses, and magnitude-based inferences. A significantly greater (P < 0.001; effect size = 2.16, very large; almost certainly higher) performance decrement was apparent using CODD (5.99 ± 1.88%) than Agility 5-0-5 performance time (2.84 ± 0.84%). The present findings indicate that change-of-direction speed measured with CODD shows promise in providing different insight and deteriorates more than total performance time during repeated sprints in basketball players. Change-of-direction deficit has potential to better isolate decrements in change-of-direction speed across repeated sprints compared with total performance time.

Dribble Deficit Enables Measurement of Dribbling Speed Independent of Sprinting Speed in Collegiate, Male, Basketball Players.

ABSTRACT: Ramirez-Campillo, R, Gentil, P, Moran, J, Dalbo, VJ, and Scanlan, AT. Dribble Deficit enables measurement of dribbling speed independent of sprinting speed in collegiate, male, basketball players. J Strength Cond Res 35(7): 2040-2045, 2021-The aim of this study was to determine the relationships between sprinting and dribbling speed in basketball during linear and change-of-direction (COD) sprints using total dribbling time and Dribble Deficit. Collegiate, male, basketball players (n = 10; 21.0 ± 1.6 years) performed linear and COD sprints with and without dribbling a ball. Linear dribbling sprints were measured for the dominant and nondominant hands, whereas COD dribbling sprints involved bilateral use of hands. Dribble Deficit was determined as the difference between total time (second) during each dribbling trial and the equivalent nondribbling trial for linear and COD sprints. Simple linear regression analyses were performed during linear and COD sprints to determine the relationship (R) and shared variance (R2) between (a) sprinting times and total dribbling times and (b) sprinting times and Dribble Deficit. Large to very large, significant relationships were evident between linear sprinting and dribbling time for dominant (R = 0.86; R2 = 0.74, p = 0.001) and nondominant hands (R = 0.80; R2 = 0.65, p = 0.005). Trivial relationships were apparent between linear sprinting time and Dribble Deficit with dominant (R = 0.10; R2 = 0.01, p = 0.778) and nondominant hands (R = 0.03; R2 = 0.00, p = 0.940). A very large relationship was evident between COD sprinting and dribbling time (R = 0.91; R2 = 0.82, p < 0.001), whereas a trivial relationship was observed between COD sprinting time and COD Dribble Deficit (R = -0.23; R2 = 0.05, p = 0.530). Dribble Deficit eliminates the strong influence of sprinting speed on outcome measures typically seen when using tests predicated on total dribbling time. Consequently, Dribble Deficit may be of added use in basketball test batteries to measure dribbling speed across linear and multidirectional movement paths.

Individualized and Fixed Thresholds to Demarcate PlayerLoad Intensity Zones Produce Different Outcomes.

ABSTRACT: Scanlan, AT, Fox, JL, Milanovic, Z, Stojanovic, E, Stanton, R, and Dalbo, VJ. Individualized and fixed thresholds to demarcate PlayerLoad intensity zones produce different outcomes. J Strength Cond Res 35(7): 2046-2052, 2021-Individualized approaches to derive intensity zones are yet to be examined using microsensor metrics in basketball. The purpose of this study was to quantify and compare the time spent in different PlayerLoad intensity zones using individualized and fixed approaches during basketball training. Thirteen semiprofessional, male basketball players were monitored across the preparatory training phase. Microsensors recorded the time spent in 6 PlayerLoad intensity zones using individualized and fixed approaches. Individualized zones were calculated relative to the peak instantaneous PlayerLoad response observed in each player across training. Fixed zones were determined following predefined cut-points set in proprietary software. The majority of training time was spent in zones 1-2 (98-99%), with a low proportion of time detected in zones 3-6 (1-2%) across approaches. The fixed approach produced greater training time in zones 2 (11.9 ± 1.2 vs. 9.3 ± 2.4 minutes; very likely large) and 3 (1.7 ± 0.8 vs. 0.8 ± 0.9 minutes; very likely moderate), was an unclear small increase in time spent in zone 1 were apparent using individualized thresholds (76.5 ± 11.2 vs. 72.9 ± 9.6 minutes). Almost certain similar time was spent in zones 4-6 across approaches. Individual analyses showed deviations across players; however, fixed PlayerLoad thresholds produced higher training time in zones 2 (moderate to very large), 3 (moderate to very large), 4 (moderate to large), and 5 (moderate) than the individualized approach in most players. Variations in outcomes between individualized and fixed approaches must be considered when quantifying the time spent working in PlayerLoad intensity zones.

Recreational Basketball Small-Sided Games Elicit High-Intensity Exercise With Low Perceptual Demand.

ABSTRACT: Stojanovic, E, Stojiljkovic, N, Stankovic, R, Scanlan, AT, Dalbo, VJ, and Milanovic, Z. Recreational basketball small-sided games elicit high-intensity exercise with low perceptual demand. J Strength Cond Res 35(11): 3151-3157, 2021-The purpose of this study was to describe and compare the internal and external load imposed on players during 1-a-side, 2-a-side, and 3-a-side recreational basketball small-sided games (SSGs). Twelve recreationally active, male college students were monitored across 10 minutes of 1-a-side, 2-a-side, and 3-a-side basketball SSG. Internal load variables included continuous measurement of heart rate (HR) responses, as well as rating of perceived exertion (RPE) and blood lactate concentration (BLa), after each game. External load variables included measurement of the total distance covered as well as the frequency of accelerations and decelerations. Blood lactate concentration and RPE were moderately (p < 0.05) greater in 1-a-side SSG than 3-a-side SSG. Total accelerations and decelerations were higher in 1-a-side and 2-a-side SSG compared with 3-a-side SSG (p < 0.05, moderate-large). All SSG formats resulted in players spending more time (p < 0.05, moderate-large) at higher HR intensities (81-100% HRmax) than lower intensities (≤80% HRmax). Furthermore, players covered greater distances (p < 0.05, large-very large) at lower intensities (0-12 km·h-1) and completed more accelerations and decelerations (p < 0.05, large-very large) at lower intensities (<2 m·s-2) than at higher intensities across SSG formats. Basketball SSG consisting of 1-3 players elicits an intermittent activity profile, promoting the extensive utilization of anaerobic and aerobic metabolism pathways, which potentially can lead to marked improvements in cardiovascular and musculoskeletal fitness in the general population when administered in recreational settings. Moreover, recreational basketball SSG with only 1 player per team elicits higher BLa, RPE, distances covered at low speeds as well as acceleration and deceleration volumes than SSG with 3 players per team.

Power-Related Determinants of Modified Agility T-test Performance in Male Adolescent Basketball Players.

ABSTRACT: Scanlan, AT, Wen, N, Pyne, DB, Stojanovic, E, Milanovic, Z, Conte, D, Vaquera, A, and Dalbo, VJ. Power-related determinants of Modified Agility T-test performance in male adolescent basketball players. J Strength Cond Res 35(8): 2248-2254, 2021-Although the Modified Agility T-test (MAT) has been advocated for assessing change-of-direction performance in basketball, the power-related attributes emphasized during the test are unknown. Therefore, the aim of this study was to identify the power-related determinants of the MAT in basketball players. A cross-sectional, descriptive research design was used whereby national- and state-level male adolescent basketball players (n = 24; 17.3 ± 0.5 years) completed a battery of power-related performance tests. The tests administered included the MAT, isometric midthigh pull, 10-m sprint, countermovement jump, 1-step vertical jump, standing long jump, and repeated lateral bound. Associations between performance during the MAT and other tests were quantified, and performance in each test was compared between faster (>50th percentile) and slower (<50th percentile) players in the MAT. The MAT exhibited large correlations (p < 0.05) with standing long jump distance (r = -0.67, R2 = 45%), countermovement jump relative peak force (r = -0.63, R2 = 39%), isometric midthigh pull relative peak force (r = -0.55, R2 = 30%), and 10-m sprint time (r = 0.53, R2 = 28%). The faster group performed better (p < 0.05) during the standing long jump (mean difference; ±90% confidence limits: 0.16; ±0.12 m) and produced greater (p < 0.05) relative peak force during the isometric midthigh pull (2.5; ±2.3 N·kg-1) and countermovement jump (2.1; ±1.8 N·kg-1) than the slower group. The MAT complements other power-related tests used in basketball and stresses basketball-specific, power-related attributes in various movement planes. These data can inform training and testing approaches to optimize change-of-direction performance in basketball.

Game format alters the physiological and activity demands encountered during small-sided football games in recreational players.

BACKGROUND: Conditioning in the form of football small-sided games (SSG) is being increasingly utilized as a health-promoting and performance-enhancing activity. OBJECTIVE: The aim of this study was to quantify and compare the physiological responses and activity demands encountered during 3-a-side, 4-a-side, and 5-a-side football SSG in recreational players. METHOD: Heart rate, blood lactate (BLa), rating of perceived exertion (RPE) and activity demands were measured across 2 × 20-min football sessions played on a 40 × 20-m pitch in 12 recreationally active college students. Data were collected over a period of two weeks using a repeated-measures crossover design. RESULTS: Mean heart rate was higher (moderate) during 5-a-side than 4-a-side (p = 0.02) and 3-a-side SSG (p < 0.001). BLa tended to be higher (small) in 3-a-side compared to 4-a-side (p = 0.12) and 5-a-side SSG (p = 0.46). The total distance covered was lower (large) during 5-a-side than 4-a-side SSG (p = 0.02), while the total number of accelerations (p = 0.01) and decelerations (p = 0.02) were higher (large) during 5-a-side than 4-a-side SSG. CONCLUSION: These data suggest: 1) 5-a-side SSG require a greater intermittent workload and exacerbated HR responses; 2) 4-a-side SSG require more sustained activity (distance); and 3) 3-a-side SSG result in higher BLa compared to other SSG formats. The observed intermittent workload and exacerbated HR response in 5-a-side SSG were likely due to greater turnover rates with more frequent interceptions. Sustained activity in 4-a-side SSG might be underpinned by format-specific structures permitting optimal team work, while isolated guarding of players in 3-a-side SSG may have exacerbated BLa responses.

Dribble Deficit quantifies dribbling speed independently of sprinting speed and differentiates between age categories in pre-adolescent basketball players.

The aims of this study were to a) quantify the relationships between sprinting and dribbling speed measured using dribble time and Dribble Deficit and b) assess the difference between age categories in sprinting and dribbling speed in pre-adolescent basketball players. Pre-adolescent, male basketball players (Total, N = 81; Under-10, n = 32, Under-9, n = 49) completed two trials of different tasks including 20-m linear sprints without dribbling, 20-m linear sprints dribbling with dominant and non-dominant hands, and change-of-direction (COD) sprints with and without dribbling. Sprinting time, dribbling time and Dribble Deficit were then calculated for each trial. Spearman rank correlations were used to assess the relationships between outcome measures for Under-9 and Under-10 players separately and combined. The Mann-Whitney U test with effect sizes (ES) was used to assess differences in outcome measures between Under-9 and Under-10 players. Moderate-to-very large significant relationships (p <0.05) between linear and COD sprinting time and dribbling time using dominant and non-dominant hands were found in Under-9, Under-10 and all players combined. Trivial-to-moderate relationships were found between sprinting time and Dribble Deficit in all age categories across linear and COD paths. Quicker performance times (p <0.05) were found for Under-10 compared to Under-9 players in all outcome measures (ES: small-to-moderate), except for COD sprinting time (p >0.05; ES: small). Dribble Deficit measures dribbling speed independently of sprinting speed across linear and COD paths in pre-adolescent basketball players and differentiates between age categories.

Physical Determinants of Division 1 Collegiate Basketball, Women's National Basketball League, and Women's National Basketball Association Athletes: With Reference to Lower-Body Sidedness.

Spiteri, T, Binetti, M, Scanlan, AT, Dalbo, VJ, Dolci, F, and Specos, C. Physical determinants of Division 1 Collegiate basketball, Women's National Basketball League, and Women's National Basketball Association athletes: with reference to lower-body sidedness. J Strength Cond Res 33(1): 159-166, 2019-In female basketball, the assumed components of success include power, agility, and the proficiency at executing movements using each limb. However, the importance of these attributes in discriminating between playing levels in female basketball has yet to be determined. The purpose of this study was to compare lower-body power, change of direction (COD) speed, agility, and lower-body sidedness between basketball athletes participating in Division 1 Collegiate basketball (United States), Women's National Basketball League (WNBL) (Australia), and Women's National Basketball Association (WNBA) (United States). Fifteen female athletes from each league (N = 45) completed a double- and single-leg countermovement jump (CMJ), static jump, drop jump, 5-0-5 COD test, and an offensive and a defensive agility test. One-way analysis of variance with post hoc comparisons were conducted to compare differences in physical characteristics (height, body mass, age) and performance outcomes (jump, COD, agility assessments) between playing levels. Separate dependent t-tests were performed to compare lower-body sidedness (left vs. right lower limbs) during the single-leg CMJ jumps (vertical jump height) and 5-0-5 COD test for each limb within each playing level. WNBA athletes displayed significantly greater lower-body power (p = 0.01-0.03) compared with WNBL athletes, significantly faster COD speed (p = 0.02-0.03), and offensive and defensive agility performances (p = 0.02-0.03) compared with WNBL and Collegiate athletes. The WNBL athletes also produced a faster defensive agility performance compared with Collegiate athletes (p = 0.02). Furthermore, WNBA and WNBL athletes exhibited reduced lower-body sidedness compared with Collegiate athletes. These findings indicate the importance of lower-body power, agility, and reduced lower-body imbalances to execute more proficient on-court movements required to compete at higher playing levels.

Dribble Deficit: A novel method to measure dribbling speed independent of sprinting speed in basketball players.

Basketball tests assessing dribbling speed predicated on total performance times are influenced by sprinting speed. This study examines an approach termed Dribble Deficit to counter this limitation by examining the relationships between sprinting and dribbling speed during linear and change-of-direction (COD) tasks measured using total performance time and Dribble Deficit. Ten semi-professional basketball players completed linear sprints and COD sprints with and without dribbling. Dribble Deficit was calculated as the difference between the best time for each dribbling trial and corresponding non-dribbling trial for linear and COD sprints. Large to very large significant relationships (P < 0.05) were evident between linear sprint and dribble times (R = 0.64-0.77, R2 = 0.41-0.59), and between COD sprint and dribble times (R = 0.88, R2 = 0.77). Conversely, trivial-small relationships were evident between linear sprint time and linear Dribble Deficit (R = 0.01-0.15, R2 = 0.00-0.02). A non-significant, moderate, negative relationship was observed between COD sprint time and COD Dribble Deficit (R = -0.45, R2 = 0.20). These findings indicate Dribble Deficit provides a more isolated measure of dribbling speed than tests using total performance times. Basketball practitioners may use Dribble Deficit to measure dribbling speed independent of sprint speed in test batteries.

Decrements in knee extensor and flexor strength are associated with performance fatigue during simulated basketball game-play in adolescent, male players.

This study quantified lower-limb strength decrements and assessed the relationships between strength decrements and performance fatigue during simulated basketball. Ten adolescent, male basketball players completed a circuit-based, basketball simulation. Sprint and jump performance were assessed during each circuit, with knee flexion and extension peak concentric torques measured at baseline, half-time, and full-time. Decrement scores were calculated for all measures. Mean knee flexor strength decrement was significantly (P < 0.05) related to sprint fatigue in the first half (R = 0.65), with dominant knee flexor strength (R = 0.67) and dominant flexor:extensor strength ratio (R = 0.77) decrement significantly (P < 0.05) associated with sprint decrement across the entire game. Mean knee extensor strength (R = 0.71), dominant knee flexor strength (R = 0.80), non-dominant knee flexor strength (R = 0.75), mean knee flexor strength (R = 0.81), non-dominant flexor:extensor strength ratio (R = 0.71), and mean flexor:extensor strength ratio (R = 0.70) decrement measures significantly (P < 0.05) influenced jump fatigue during the entire game. Lower-limb strength decrements may exert an important influence on performance fatigue during basketball activity in adolescent, male players. Consequently, training plans should aim to mitigate lower-limb fatigue to optimise sprint and jump performance during game-play.

Power Testing in Basketball: Current Practice and Future Recommendations.

Wen, N, Dalbo, VJ, Burgos, B, Pyne, DB, and Scanlan, AT. Power testing in basketball: Current practice and future recommendations. J Strength Cond Res 32(9): 2686-2700, 2018-Numerous foundational movements performed during basketball are predicated on underlying power-related attributes, including speed, change-of-direction (COD), and jumping. Accordingly, fitness testing batteries for basketball have incorporated an assortment of linear speed tests, COD tests, and jump tests. However, because of the wide variety of testing options, it is difficult for basketball practitioners to select appropriate testing protocols for the assessment of power-related attributes. As a result, there is a need to review the relevant literature to identify game-specific, power-related attributes important in basketball and the most appropriate tests available to assess power-related attributes for basketball practitioners. Therefore, the aims of this review were to: (a) identify essential power-related attributes important in basketball; (b) discuss the suitability of common and novel power-related tests; and (c) provide recommendations for future research and best practice approaches for basketball coaching staff. In this review, we propose a series of novel tests that are more targeted and specific to basketball movements including: (a) 5- and 10-m linear sprints, (b) modified agility T-test, (c) change-of-direction deficit (CODD), (d) lateral bound, (e) Sargent jump, (f) one-step jump, and (g) isometric midthigh pull test. Improved testing of power-related attributes should enable basketball practitioners to develop targeted training plans for enhancing player performance.

Heart Rate Monitoring in Basketball: Applications, Player Responses, and Practical Recommendations.

Berkelmans, DM, Dalbo, VJ, Kean, CO, Milanovic, Z, Stojanovic, E, Stojiljkovic, N, and Scanlan, AT. Heart rate monitoring in basketball: applications, player responses, and practical recommendations. J Strength Cond Res 32(8): 2383-2399, 2018-The aims of this review were to collate the existing literature encompassing heart rate (HR) monitoring in basketball to (a) identify the applications of HR measurement; (b) report HR responses in male and female players during training and game-play; (c) evaluate use of current HR-based training load models; and (d) provide recommendations for future research and best practice approaches for basketball practitioners. Heart rate monitoring in basketball carries 3 primary applications: (a) monitoring exercise intensity; (b) assessing player fatigue status; and (c) quantifying internal training load. When interpreting the available training and game-play HR data in basketball players, key differences have been observed between playing positions and playing levels. Sex- and age-based differences in HR responses during basketball training and game-play are apparent across separate studies; however, further research exploring HR responses in wider player groups is needed, especially in female and junior players. There is also a lack of research directly comparing player HR responses during training and game-play to ascertain the effectiveness of different drills in preparing players for competition. Heart rate-based models have been frequently used to quantify the internal training load in basketball players, including Banister's Training Impulse (TRIMP), Lucia's TRIMP, and Edwards' Summated-Heart-Rate-Zones (SHRZ). The SHRZ model seems to hold practical advantages and better detect changes in player responses across training cycles compared with other approaches. Practical outcomes of this review center on recommendations for position-specific training plans, drills to promote desired cardiovascular stress, analysis of HR outcome measures, and ideal training load monitoring approaches.

Influence of Different Methods to Determine Maximum Heart Rate on Training Load Outcomes in Basketball Players.

Berkelmans, DM, Dalbo, VJ, Fox, JL, Stanton, R, Kean, CO, Giamarelos, KE, Teramoto, M, and Scanlan, AT. Influence of different methods to determine maximum heart rate on training load outcomes in basketball players. J Strength Cond Res 32(11): 3177-3185, 2018-The summated-heart-rate-zones (SHRZ) approach uses heart rate (HR) responses relative to maximum HR (HRmax) to calculate the internal training load (TL). Age-predicted, test-derived, and session-based approaches have all been used to determine HRmax in team sports. The purpose of this study was to determine the effects of using age-predicted, test-derived, and session-based HRmax responses on SHRZ TL in basketball players. Semiprofessional, male basketball players (N = 6) were analyzed during the preparatory training phase. Six age-based approaches were used to predict HRmax including Fox (220 - age); Hossack (206 - [0.567 × age]); Tanaka (208 - [0.7 × age]); Nikolaidis (223 - [1.44 × age]); Nes (211 - [0.64 × age]); and Faff (209.9 - [0.73 × age]). Test-derived HRmax was taken as the highest HR during the Yo-Yo intermittent recovery test (Yo-Yo IRT), whereas session-based HRmax was taken as the higher HR seen during the Yo-Yo IRT or training sessions. Comparisons in SHRZ TL were made at group and individual levels. No significant group differences were evident between SHRZ approaches. Effect size analyses revealed moderate (d = 0.60-0.79) differences between age-predicted, test-derived, and session-based methods across the group and individually in 2 players. The moderate differences between approaches suggest age-predicted, test-derived, and session-based methods to determine HRmax are not interchangeable when calculating SHRZ. Basketball practitioners are encouraged to use individualized HRmax directly measured during field-based tests supplemented with higher HR responses evident during training sessions and games when calculating the SHRZ TL to ensure greatest accuracy.

Effects of Hydrolyzed Whey versus Other Whey Protein Supplements on the Physiological Response to 8 Weeks of Resistance Exercise in College-Aged Males.

OBJECTIVE: The objective of this study was to compare the chronic effects of different whey protein forms on body composition and performance when supplemented with resistance training. METHODS: Resistance-trained men (N = 56, 21.4 ± 0.4 years, 79.5 ± 1.0 kg) participated in an 8-week resistance training regimen (2 upper-body sessions and 2 lower-body sessions per week) and received one of 4 double-blinded treatments: 30 g/serving carbohydrate placebo (PLA) or 30 g/serving protein from either (a) 80% whey protein concentrate (WPC), (b) high-lactoferrin-containing WPC (WPC-L), or (c) extensively hydrolyzed WPC (WPH). All subjects consumed 2 servings of treatment per day; specifically, once immediately before and after training and between meals on nontraining days. Blood collection, one repetition maximum (1RM) testing for bench press and hack squat, and body composition assessment using dual-energy x-ray absorptiometry (DXA) occurred prior to training and 48 hours following the last training session. RESULTS: Total body skeletal muscle mass increased in all groups (p < 0.0125). There were similar between-group increases in upper-body (4%-7%, analysis of covariance [ANCOVA] interaction p = 0.73) and lower-body (24%-35%, ANCOVA interaction p = 0.85) 1RM strength following the intervention. Remarkably, WPH reduced fat mass (-6%), which was significantly different from PLA (+4.4%, p < 0.0125). No time or between-group differences were present for serum markers of health, metabolism, or muscle damage, with the exception of blood urea nitrogen being significantly lower for WPH than WPC (p < 0.05) following the intervention. CONCLUSIONS: WPH may augment fat loss but did not provide any other advantages when used in combination with resistance training. More mechanistic research is needed to examine how WPH affects adipose tissue physiology.

Effects of high-intensity interval training on cardiometabolic health: a systematic review and meta-analysis of intervention studies.

The current review clarifies the cardiometabolic health effects of high-intensity interval training (HIIT) in adults. A systematic search (PubMed) examining HIIT and cardiometabolic health markers was completed on 15 October 2015. Sixty-five intervention studies were included for review and the methodological quality of included studies was assessed using the Downs and Black score. Studies were classified by intervention duration and body mass index classification. Outcomes with at least 5 effect sizes were synthesised using a random-effects meta-analysis of the standardised mean difference (SMD) in cardiometabolic health markers (baseline to postintervention) using Review Manager 5.3. Short-term (ST) HIIT (<12 weeks) significantly improved maximal oxygen uptake (VO2 max; SMD 0.74, 95% CI 0.36 to 1.12; p<0.001), diastolic blood pressure (DBP; SMD -0.52, 95% CI -0.89 to -0.16; p<0.01) and fasting glucose (SMD -0.35, 95% CI -0.62 to -0.09; p<0.01) in overweight/obese populations. Long-term (LT) HIIT (≥12 weeks) significantly improved waist circumference (SMD -0.20, 95% CI -0.38 to -0.01; p<0.05), % body fat (SMD -0.40, 95% CI -0.74 to -0.06; p<0.05), VO2 max (SMD 1.20, 95% CI 0.57 to 1.83; p<0.001), resting heart rate (SMD -0.33, 95% CI -0.56 to -0.09; p<0.01), systolic blood pressure (SMD -0.35, 95% CI -0.60 to -0.09; p<0.01) and DBP (SMD -0.38, 95% CI -0.65 to -0.10; p<0.01) in overweight/obese populations. HIIT demonstrated no effect on insulin, lipid profile, C reactive protein or interleukin 6 in overweight/obese populations. In normal weight populations, ST-HIIT and LT-HIIT significantly improved VO2 max, but no other significant effects were observed. Current evidence suggests that ST-HIIT and LT-HIIT can increase VO2 max and improve some cardiometabolic risk factors in overweight/obese populations.

Intramuscular phosphagen status and the relationship to muscle performance across the age spectrum.

PURPOSE: To examine age-related differences in intramuscular concentrations of adenosine triphosphate (ATP), free creatine (FCr), phosphocreatine (PCr) and total creatine (TCr) and if these differences were related to muscle performance. METHODS: Forty-two healthy, non-sedentary, males between 20 and 76 years provided muscle samples to determine [ATP], [FCr], [PCr], and [TCr]. Maximal strength and endurance were assessed and correlated with intramuscular variables. RESULTS: Intramuscular [ATP] decreased by 13.5% (p = 0.013) in the older cohort (18.0 ± 0.6 mmol/kg dry wt) vs. the young cohort (20.8 ± 0.9 mmol/kg dry wt) and was significantly correlated to age (r = -0.38, p = 0.008). No other differences were observed between age groups for intramuscular [PCr], [FCr], [TCr], or [PCr]:[TCr] (p > 0.05). The older cohort consumed significantly less (p < 0.05) dietary protein when compared to the young cohort. Bivariate correlations were found for intramuscular [ATP] and lower body 1RM (r = 0.24, p = 0.066), leg press volume and free creatine (r = 0.325, p = 0.036) and leg press repetitions and free creatine (r = 0.373, p = 0.015). Partial correlations controlling for age eliminated the relationship between [ATP] and 1RM while intramuscular free creatine and leg press repetitions remained significant (p < 0.05) and leg press volume approached significance (p = 0.095). CONCLUSION: These results expand upon previous observations indicative of age-related reductions in intramuscular [ATP] and dietary protein intake. The lack of change in other intramuscular PCr system markers are suggestive of dysfunctions at the mitochondrial level while the impact of neuromuscular changes, lean mass cross-sectional area and differences in physical activity are also important.

O-GlcNAc protein modification in C2C12 myoblasts exposed to oxidative stress indicates parallels with endogenous antioxidant defense.

A growing body of evidence demonstrates the involvement of protein modification with O-linked ß-N-acetylglucosamine (O-GlcNAc) in the stress response and its beneficial effects on cell survival. Here we investigated protein O-GlcNAcylation in skeletal muscle cells exposed to oxidative stress and the crosstalk with endogenous antioxidant system. The study focused on antioxidant enzymes superoxide dismutase 2 (SOD2), catalase (CAT), and glutathione peroxidase 1 (GPX1), and transcriptional regulators proliferator-activated receptor gamma coactivator 1-α (PGC-1α) and forkhead box protein O1 (FOXO1), which play important roles in oxidative stress response and are known to be O-GlcNAc-modified. C2C12 myoblasts were subjected to 24 h incubation with different reagents, including hydrogen peroxide, diethyl maleate, high glucose, and glucosamine, and the inhibitors of O-GlcNAc cycling enzymes. Surprisingly, O-GlcNAc levels were significantly increased only with glucosamine, whilst other treatments showed no effect. Significant changes at the mRNA level were observed with concomitant upregulation of the genes for O-GlcNAc enzymes and stress-related proteins with oxidizing agents and downregulation of these genes with agents promoting O-GlcNAcylation. Our findings suggest a role of O-GlcNAc in the stress response and indicate an inhibitory mechanism controlling O-GlcNAc levels in the muscle cells. This could represent an important homeostatic regulation of the cellular defense system.

Glutathione depletion and acute exercise increase O-GlcNAc protein modification in rat skeletal muscle.

Post-translational modification of intracellular proteins with O-linked ß-N-acetylglucosamine (O-GlcNAc) profoundly affects protein structure, function, and metabolism. Although many skeletal muscle proteins are O-GlcNAcylated, the modification has not been extensively studied in this tissue, especially in the context of exercise. This study investigated the effects of glutathione depletion and acute exercise on O-GlcNAc protein modification in rat skeletal muscle. Diethyl maleate (DEM) was used to deplete intracellular glutathione and rats were subjected to a treadmill run. White gastrocnemius and soleus muscles were analyzed for glutathione status, O-GlcNAc and O-GlcNAc transferase (OGT) protein levels, and mRNA expression of OGT, O-GlcNAcase and glutamine:fructose-6-phosphate amidotransferase. DEM and exercise both reduced intracellular glutathione and increased O-GlcNAc. DEM upregulated OGT protein expression. The effects of the interventions were significant 4 h after exercise (P < 0.05). The changes in the mRNA levels of O-GlcNAc enzymes were different in the two muscles, potentially resulting from different rates of oxidative stress and metabolic demands between the muscle types. These findings indicate that oxidative environment promotes O-GlcNAcylation in skeletal muscle and suggest an interrelationship between cellular redox state and O-GlcNAc protein modification. This could represent one mechanism underlying cellular adaptation to oxidative stress and health benefits of exercise.

Physiological and Fatigue Responses Associated With Male and Mixed-Gender Ultimate Frisbee Game Play.

The aims of this study were to describe the physiological and fatigue responses associated with indoor Ultimate Frisbee game play, compare exercise intensities attained to current activity guidelines, and compare responses between male and mixed-gender game formats. A between-subjects (game format) repeated-measures (time points) observational experimental design was used. Subjects competed in male (n = 10; age: 26.3 ± 7.6 years) or mixed-gender (males: n = 4; 28.5 ± 5.7 years; females: n = 6; 28.3 ± 8.1 years) indoor Ultimate Frisbee game play. Games consisted of 10-minute halves, with heart rate (HR), blood lactate concentration ([BLa]), rating of perceived exertion, and 5-m and 20-m sprint times measured. Durations spent in HR-derived intensity zones and sprint decrements were calculated across games. Mixed-gender game play produced significantly (p ≤ 0.05) higher relative HR (94.3 ± 5.1% vs. 89.6 ± 4.8% HRmax) and [BLa] (8.31 ± 2.22 mmol·L vs. 4.68 ± 1.89 mmol·L) than male game play. Significantly (p ≤ 0.05) longer durations were spent at vigorous (male: 60.2 ± 26.1%; mixed-gender: 36.8 ± 34.8%) and near-maximal (male: 31.6 ± 27.6%; mixed-gender: 58.6 ± 37.7%) exercise intensities than moderate (3.9-7.2%), light (0.7-1.0%), and very light (0-0.1%) intensities in both formats. Limited physiological and sprint fatigue was apparent across games. Subjects primarily performed at vigorous and near-maximal intensities during Ultimate Frisbee. The greater physiological demands encountered during mixed-gender game play might be attributed to underlying gender-mediated cardiovascular differences. These findings support the efficacy of Ultimate Frisbee as a prescriptive exercise tool for health benefit.

Fluctuations in Activity Demands Across Game Quarters in Professional and Semiprofessional Male Basketball.

Examination of activity demands and stoppage durations across game periods provides useful insight concerning fatigue, tactical strategies, and playing pace in team sports such as basketball. Therefore, the aims of this study were to quantify and compare game activity fluctuations across quarters in professional and semiprofessional basketball players. Video-based time-motion analyses were conducted across multiple games. Frequencies, total durations (in seconds), total distances (in meters), and mean velocities (in meters per second) were calculated for low-intensity movement (≤3 m·s), high-intensity movement (>3 m·s), shuffling, and dribbling activity. Frequencies were determined for jumping and upper-body activity; stoppage durations were also calculated. Separate repeated-measures analysis of variance and Cohen's d were used to identify significant differences and quantify the effect sizes between game quarters for all outcome measures, respectively. Pearson correlation analyses were performed to determine the relationship between stoppage duration and all activity measures. The results showed significantly (p ≤ 0.05) reduced dribbling (3.09 ± 0.03 m·s vs. 2.81 ± 0.01 m·s) and total (2.22 ± 0.04 m·s vs. 2.09 ± 0.03 m·s) activity velocities during the third compared with the first quarter in professional players. Furthermore, effect size analyses showed greater decreases in high-intensity (professional: d = 1.7-5.4; semiprofessional: d = 0.3-1.7), shuffling (professional: d = 2.3-3.2; semiprofessional: d = 1.4-2.1), and total (professional: d = 1.0-4.9; semiprofessional: d = 0.3-0.8) activity and increases in dribbling (professional: d = 1.4-4.7; semiprofessional: d = 2.5-2.8) with game progression in professional players. In semiprofessional players, stoppage duration was significantly (p ≤ 0.05) related to various low-intensity (R = 0.64-0.72), high-intensity (R = 0.65-0.72), and total (R = 0.63-0.73) activity measures. Although not directly measured, the observed game activity fluctuations were likely because of a combination of physiological (e.g., muscle glycogen depletion, dehydration), tactical (e.g., ball control, game pace), and game-related (e.g., time-outs, player fouls) factors. Basketball coaches can use the provided data to (a) develop more precise training plans and management strategies, (b) elevate semiprofessional player performance closer to the professional level, and (c) incorporate tactical strategies to maximize the benefits of stoppages.