Effects of a Short-Term Heat Acclimation Protocol in Elite Amateur Boxers.

ABSTRACT: Stone, BL, Ashley, JD, Skinner, RM, Polanco, JP, Walters, MT, Schilling, BK, and Kellawan, JM. Effects of a short-term heat acclimation protocol in elite amateur boxers. J Strength Cond Res 36(7): 1966-1971, 2022-Boxing requires proficient technical and tactical skills coupled with high levels of physiological capacity. Although heat and humidity negatively affect acute exercise performance, short-term exercise training in hot and humid environments can lead to physiological adaptations that enhance exercise performance in both hot and thermoneutral conditions. In highly trained endurance athletes, exercise-induced acclimation can occur in as little as 5 days (known as short-term heat acclimation [STHA]). However, the impact of a 5-day heat acclimation (5-DayHA) in combat athletes, such as elite amateur boxers, is unknown. The aim of the present investigation was to determine whether a 5-DayHA improves aerobic performance in a thermoneutral environment and causes positive physiological adaptations in elite boxers. Seven elite amateur boxers underwent a 5-DayHA protocol, consisting of 60-minute exercise sessions in an environmental chamber at 32 °C and 70% relative humidity. Repeat sprint test (RST) evaluated aerobic performance in a thermoneutral environment 24 hours before and after the 5-DayHA. Presession and postsession hydration status (urine specific gravity) and body mass were assessed. After a 5-DayHA period, boxers significantly improved RST performance (13 ± 7 to 19 ± 7 sprints, d = 0.92, p = 0.03) but not pre-exercise hydration status (1.02 ± 0.01 to 1.01 ± 0.01, d = 0.82, p = 0.07). Therefore, these findings suggest 5-DayHA enhances aerobic performance in elite-level amateur boxers and may provide a viable training option for elite combat athletes.

Effects of an Experimental vs. Traditional Military Training Program on 2-Mile Run Performance During the Army Physical Fitness Test.

Stone, BL, Heishman, AD, and Campbell, JA. The effects of an experimental vs. traditional military training program on 2-mile run performance during the army physical fitness test. J Strength Cond Res 34(12): 3431-3438, 2020-The purpose of this study was to compare the effects of an experimental vs. traditional military run training on 2-mile run ability in the Army Reserve Officers' Training Corps cadets. Fifty college-aged cadets were randomly placed into 2 groups and trained for 4 weeks with either an experimental running program (EXP, n = 22) comprised rating of perceived exertion (RPE) intensity-specific, energy system-based intervals or with traditional military running program (TRA, n = 28) using a crossover study design. A 2-mile run assessment was performed just before the start, at the end of the first 4 weeks, and again after the second 4 weeks of training after crossover. The EXP program significantly decreased 2-mile run times (961.3 ± 155.8 seconds to 943.4 ± 140.2 seconds, p = 0.012, baseline to post 1), whereas the TRA group experienced a significant increase in run times (901.0 ± 79.2 vs. 913.9 ± 82.9 seconds) over the same training period. There was a moderate effect size (d = 0.61, p = 0.07) for the experimental run program to "reverse" the adverse effects of the traditional program within the 4-week training period (post 1 to post 2) after treatment crossover. Thus, for short-term training of military personnel, RPE intensity-specific running program comprising aerobic and anaerobic system development can enhance 2-mile run performance superior to a traditional program while reducing training volume (60 minutes per session vs. 43.2 minutes per session, respectively). Future research should extend the training period to determine efficacy of this training approach for long-term improvement of aerobic capacity and possible reduction of musculoskeletal injury.

Understanding cognitive performance during exercise in Reserve Officers' Training Corps: establishing the executive function-exercise intensity relationship.

Military performance depends on high-level cognition, specifically executive function (EF), while simultaneously performing strenuous exercise. However, most studies examine cognitive performance following, not during, exercise. Therefore, our aim was to examine the relationship between EF and exercise intensity. Following familiarization, 13 Reserve Officers' Training Corp cadets (age = 19.6 ± 2 yr, five women) completed a graded exercise test (GxT) and two executive function exercise tests (EFETs) separated by a duration of ≥24 h. The EFET was a combined iPad-based EF test (Cedar Operator Workload Assessment Tool) and GxT. Heart rate (HR) and prefrontal cortex (PFC) oxygenation [near-infrared spectroscopy (NIRS)] were continuously recorded. The EF score was analyzed for accuracy of responses (%hit rate). Heart rate reserve was calculated to normalize exercise intensity (%HRR). For PFC oxygenation recordings, NIRS variables were used to calculate the tissue saturation index (%TSI). Data from EFET trials were averaged into a singular response. The %hit rate declined at heart rate reserves (HRRs) of ≥80%, reaching nadir at 100% HRR (74.09 ± 10.63%, P < 0.01). The tissue saturation index (TSI) followed a similar pattern, declining at ≥70% of HRR and at a greater rate during EFET compared with during GxT (P < 0.01), reaching a nadir in both conditions at 100% HRR (60.39 ± 2.94 vs. 63.13 ± 3.16%, P < 0.01). Therefore, EF decline is dependent on exercise intensity, as is %TSI. These data suggest that reductions in EF during high-intensity exercise are at least in part related to attenuated PFC oxygenation. Thus, interventions that improve PFC oxygenation may improve combined exercise and EF performance.NEW & NOTEWORTHY The executive functioning aspect of cognition was evaluated during graded exercise in Reserve Officers' Training Corps cadets. Executive function declined at exercise intensities of ≥80% of heart rate reserve. The decline in executive function was coupled with declines in the oxygenation of the prefrontal cortex, the brain region responsible for executive functioning. These data define the executive function-exercise intensity relationship and provide evidence supporting the reticular activation hypofrontality theory as a model of cognitive change.

Neuromuscular Fatigue in Pitchers Across a Collegiate Baseball Season.

Stone, BL and Schilling, BK. Neuromuscular fatigue in pitchers across a collegiate baseball season. J Strength Cond Res 34(7): 1933-1937, 2020-Neuromuscular fatigue in baseball pitchers has become an important aspect of injury risk. It is imperative to understand how fatigue is manifested to enhance resiliency and mitigate injury risk. Secondarily, collecting data on neuromuscular characteristics of baseball pitchers provides a framework to address these concerns. Using the countermovement jump, this study observed neuromuscular performance during the preseason, midseason, and postseason of a collegiate baseball season with college baseball pitchers. No statistically significant changes were noted in any of the main variables at any testing timepoint (p > 0.05). However, several variables, including concentric mean force (ConMF, d = 0.59) and concentric peak force (ConPF, d = 0.59) in addition to eccentric mean force (EccMF, d = 0.54) and eccentric mean power (EccMP, d = -0.66), displayed moderate effects from preseason testing to midseason testing. Furthermore, jump height displayed a large negative effect from preseason to midseason (d = -0.89). Secondarily, descriptive data for both concentric and eccentric variables were also determined from the present findings. There were moderate changes in neuromuscular fatigue in Division I collegiate pitchers across a competitive season and has provided descriptive data for neuromuscular characteristics in collegiate baseball pitchers.

The High Precision of Functional and Neuromuscular Measures to Classify Sarcopenia in Older Women.

BACKGROUND AND PURPOSE: Previous literature suggests that reductions in appendicular skeletal mass (ASM) may have a greater detrimental effect than total lean body mass regarding the onset and progression of sarcopenia. Unfortunately, limited access to equipment that accurately determines ASM often leads to many individuals remaining undiagnosed and experiencing functional decline. Therefore, the purpose of this investigation was to determine the ability of functional and neuromuscular measures to identify ASM in older women. METHODS: Forty-one (sarcopenic n = 15) older women underwent body composition analysis via dual-energy X-ray absorptiometry (DXA) and performed the following measures: bench press (BP) 1-repetition maximum strength (1RM), vertical jump height and power, handgrip strength, Timed Up and Go test, Berg Balance Scale testing, and bench press power testing at 20%, 40%, and 60% 1RM. RESULTS AND DISCUSSION: Regression analyses revealed 3 significant models accounting for 93.8%, 91.1%, and 86.4% of the variance in DXA-derived ASM. Paired-samples t tests revealed no significant differences between model-derived and DXA-derived ASM for each model, and each model was significantly correlated to DXA-derived ASM (P < .001). In addition, each model revealed a strong ability to appropriately classify sarcopenia status, with the area under the curve values ranging from 0.86 to 0.93. The present data indicate that ASM can be determined with high precision by measuring outcome variables such as jump power, body weight, and grip strength in older women. CONCLUSIONS: Therefore, the present models could be used to identify, screen, or classify older women as sarcopenic, ultimately allowing the implementation of interventions aimed at decreasing the difficulty of activities of daily living and increasing quality of life.