Influence of Environmental Conditions on Performance and Heart Rate Responses to the 30-15 Incremental Fitness Test in Rugby Union Athletes

The Cumulative Impacts of Fatigue during Overload Training Can Be Tracked Using Field-Based Monitoring of Running Stride Interval Correlations

Integrating running gait coordination assessment into athlete monitoring systems could provide unique insight into training tolerance and fatigue-related gait alterations. This study investigated the impact of an overload training intervention and recovery on running gait coordination assessed by field-based self-testing. Fifteen trained distance runners were recruited to perform 1-week of light training (baseline), 2 weeks of heavy training (high intensity, duration, and frequency) designed to overload participants, and a 10-day light taper to allow recovery and adaptation. Field-based running assessments using ankle accelerometry and online short recovery and stress scale (SRSS) surveys were completed daily. Running performance was assessed after each training phase using a maximal effort multi-stage running test-to-exhaustion (RTE). Gait coordination was assessed using detrended fluctuation analysis (DFA) of a stride interval time series. Two participants withdrew during baseline training due to changed personal circumstances. Four participants withdrew during heavy training due to injury. The remaining nine participants completed heavy training and were included in the final analysis. Heavy training reduced DFA values (standardised mean difference (SMD) = -1.44 ± 0.90; p = 0.004), recovery (SMD = -1.83 ± 0.82; p less than 0.001), performance (SMD = -0.36 ± 0.32; p = 0.03), and increased stress (SMD = 1.78 ± 0.94; p = 0.001) compared to baseline. DFA values (p = 0.73), recovery (p = 0.77), and stress (p = 0.73) returned to baseline levels after tapering while performance trended towards improvement from baseline (SMD = 0.28 ± 0.37; p = 0.13). Reduced DFA values were associated with reduced performance (r2 = 0.55) and recovery (r2 = 0.55) and increased stress (r2 = 0.62). Field-based testing of running gait coordination is a promising method of monitoring training tolerance in running athletes during overload training.

Hot water immersion; potential to improve intermittent running performance and perception of in-game running ability in semi-professional Australian Rules Footballers?

This study investigated whether hot water immersion (HWI) could heat acclimate athletes and improve intermittent running performance and perception of in-game running ability, during a competitive Australian Rules Football (ARF) season. Fifteen male semi-professional ARF athletes (Mean (SD); age: 22 (3) years, height: 182.3 (6.5) cm, mass: 80.5 (5.1) kg) completed either HWI (HEAT, N = 8, 13 (2) sessions, 322 (69) min exposure, 39.5 (0.3) °C) or acted as a control (CON, N = 7, no water immersion) over 6-weeks. Athletes completed a 30–15 Intermittent Fitness Test pre and post-intervention to assess intermittent running performance (VIFT), with perception of in-game running ability measured. Heat acclimation was determined via change in resting plasma volume, as well as physiological and perceptual responses during HWI. HEAT elicited large PV expansion (mean ± 90% CI: d = 1.03 ± 0.73), large decreases in heart rate (d = -0.89 ± 0.70), thermal sensation (d = -2.30 ± 1.15) and tympanic temperature (d = -1.18 ± 0.77). Large improvements in VIFT were seen in HEAT (d = 1.67 ± 0.93), with HEAT showing a greater improvement in VIFT when compared to CON (d = 0.81 ± 0.88). HEAT also showed greater belief that in-game running ability improved post-intervention (d = 2.15 ± 1.09) compared to CON. A 6-week HWI intervention can elicit heat acclimation, improve perception of in-game running ability, and potentially improve VIFT in semi-professional ARF athletes.

Benefits to Performance and Well-Being of Nature-Based Exercise: A Critical Systematic Review and Meta-Analysis

Prior reviews point to the superior benefits of exercising in nature vs in conventional indoor venues, particularly in terms of well-being. However, physical exercise performance, neither in terms of efficacy nor efficiency, has not been sufficiently addressed by past reviews of this topic. Therefore, we conducted both a systematic review and meta-analysis of the experimental literature that relates to differences in exercise performance and well-being between exercising in nature and in conventional indoor venues. Forty-nine relevant studies─the outcome data of which were used for the systematic review─were located within the Web of Science, PubMed, and Scopus databases. The meta-analyses, using data from twenty-four of the relevant studies, revealed no significant overall environmental effect on task performance efficacy outcomes (p = 0.100). For nature-based exercise, however, marginally positive cognitive performance outcomes (p = 0.059), lower ratings of perceived exhaustion (p = 0.001), and higher levels of vigor (p = 0.017) were observed, indicating higher performance efficiency. As for the effects of environment on well-being, positive affect was significantly higher for nature-based exercise (p = 0.000), while perceived stress was significantly higher for indoor exercise (p = 0.032). These results must, however, be interpreted with caution. High levels of bias and between-study heterogeneity were observed. Nonetheless, given several noticeable trends in the results, it may be that exercising in nature enhances the efficiency of exercise task performance to a greater extent than does indoor exercise.

Submaximal Fitness Tests in Team Sports: A Theoretical Framework for Evaluating Physiological State

Team-sports staff often administer non-exhaustive exercise assessments with a view to evaluating physiological state, to inform decision making on athlete management (e.g., future training or recovery). Submaximal fitness tests have become prominent in team-sports settings for observing responses to a standardized physical stimulus, likely because of their time-efficient nature, relative ease of administration, and physiological rationale. It is evident, however, that many variations of submaximal fitness test characteristics, response measures, and monitoring purposes exist. The aim of this scoping review is to provide a theoretical framework of submaximal fitness tests and a detailed summary of their use as proxy indicators of training effects in team sports. Using a review of the literature stemming from a systematic search strategy, we identified five distinct submaximal fitness test protocols characterized in their combinations of exercise regimen (continuous or intermittent) and the progression of exercise intensity (fixed, incremental, or variable). Heart rate-derived indices were the most studied outcome measures in submaximal fitness tests and included exercise (exercise heart rate) and recovery (heart rate recovery and vagal-related heart rate variability) responses. Despite the disparity between studies, these measures appear more relevant to detect positive chronic endurance-oriented training effects, whereas their role in detecting negative transient effects associated with variations in autonomic nervous system function is not yet clear. Subjective outcome measures such as ratings of perceived exertion were less common in team sports, but their potential utility when collected alongside objective measures (e.g., exercise heart rate) has been advocated. Mechanical outcome measures either included global positioning system-derived locomotor outputs such as distance covered, primarily during standardized training drills (e.g., small-sided games) to monitor exercise performance, or responses derived from inertial measurement units to make inferences about lower limb neuromuscular function. Whilst there is an emerging interest regarding the utility of these mechanical measures, their measurement properties and underpinning mechanisms are yet to be fully established. Here, we provide a deeper synthesis of the available literature, culminating with evidence-based practical recommendations and directions for future research.

Influence of Hot Environment on Pitching and Hitting Performance in Professional Baseball

ABSTRACT

Huang, J-H, Chiu, Y-C, and Chang, C-K. The influence of hot environment on pitching and hitting performance in professional baseball. J Strength Cond Res XX(X): 000-000, 2021-Baseball is usually played outdoors during the warmest months of the year. The long exposure to a hot environment may lead to hyperthermia and subsequent impaired cognitive function, which is crucial for hitting and pitching performance in baseball. The purpose of this study was to investigate the effect of apparent temperature on pitching and hitting performance in Chinese Professional Baseball League games in Taiwan. Each pitched and batted ball from a total of 480 regular season games in 2018 and 2019 was analyzed. Each game was categorized into one of the 4 groups on the basis of the average apparent temperature at which it was played: cold (below 21° C), warm (21-28° C), hot (28-34° C), or extremely hot (above 34° C). Differences in pitching and hitting variables were compared across the 4 groups. In the extremely hot environment, slugging percentage, isolated power, base on balls per 9 innings, home runs per 9 innings, and walks plus hits per inning were all significantly higher than those in the other 3 environments. The results suggest that offensive production was significantly increased in extremely hot environments in the Chinese Professional Baseball League. It is recommended that pitchers could adopt cooling interventions to alleviate the decline in performance in an extremely hot environment.