Greig Watson

Introduction: Strenuous exercise results in ischemia that damages the intestinal wall and compromises gut integrity. As the gut influences an athlete’s health, both physiologically and psychologically, exercise induced gut damage (EIGD) may contribute to fatigue, gastrointestinal symptoms, inflammation, and de-motivation, ultimately reducing performance. Estrogen may have protective effects in the gastrointestinal system, however, females make up only 15% of participants in studies pertaining to EIGD and thus are largely absent from the evidence base used to inform recommendations around gut issues in training and performance. The aim of this protocol is to determine relationships between sex hormones and EIGD. Methods: Eight females with a natural menstrual cycle were recruited (age: 29 ± 8 years, weight: 65.4 ± 12.3 kg, VO 2max : 44.2 ± 5.8 ml·kg -1 ·min -1 ). Participants completed an initial maximal oxygen consumption test to determine intensity for the experimental trials which were completed during the early follicular (EF) and late follicular (LF) phases of the menstrual cycle. The order of menstrual phase for each trial was randomized. Hormone status was verified using a three-step method: menstrual cycle tracking throughout the project, urinary luteinizing hormone surge, and confirmatory blood tests. At each trial, participants ran for 60 minutes on a treadmill in a climate controlled chamber in 21°C and 40% relative humidity at a velocity equivalent to 90% of their second ventilatory threshold. Blood samples were taken pre (PRE)- and immediately post-exercise (POST) and analyzed for plasma concentrations of intestinal fatty acid binding protein to determine enterocyte damage, and serum hormonal concentrations (estrogen and progesterone). Gastrointestinal symptoms were assessed using a standardized visual analogue scale. Heart rate, lactate, VO 2 and rating of perceived exertion were recorded at 10 minute intervals throughout each trial. Results: Pre-exercise I-FABP was not different between the high estrogen LF phase compared to the low estrogen EF phase (p = 0.88). Post-exercise I-FABP increased compared to pre-exercise values in both phases (EF median (range) PRE: 416 (217-2246) pg·mL -1 to POST 1164 (392 – 3352) pg·mL -1 , p = 0.008; LF PRE: 444 (215 – 1484) pg·mL -1 to POST: 1012 (353 – 2818) pg·mL -1 , p = 0.05. However, there was no difference in post-exercise I-FABP between the phases, either as absolute values (p = 0.36) or % change (p = 0.54). GI symptoms were most commonly reported in the early follicular phase. Discussion: There is conflicting evidence pertaining to the influence of the menstrual cycle for female athletes, primarily due to poor and inconsistent methodological practices related to determining hormonal status. Understanding menstrual cycle influences in susceptibility to intestinal damage may inform athlete training and competition load with regards to optimizing performance and recovery. This is a novel protocol for the determination of menstrual cycle influences on EIGD. Despite the small sample size, expected patterns of hormones and hypothesized patterns of EIDG were observed, but the data do not provide evidence that the menstrual cycle impacts on the development of EIGD when comparing the high estrogen phase to the low estrogen phase. This research was supported by an Australian Government Research Training Program (RTP) Scholarship This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Introduction and aims
Women’s rugby sevens is a rapidly growing sport that imposes unique match-play movement demands on participants. This research investigated the effect of contextual factors on the match-play movement demands of international and domestic women’s rugby sevens players.

Methods
An observational, longitudinal study design was conducted to characterise Global Navigation Satellite Systems (GNSS) match-play movement demands in international (n = 23) and domestic (n = 42) players across two seasons and nine series of an elite domestic women’s dual-level rugby sevens tournament. In total, across the 65 players, 1461 matches were analysed. Match-play movement demands were assessed through distance, speed, and acceleration metrics using 10 and 15 Hz (5 Hz interpolated to 15 Hz) GNSS devices. Contextual factors were grouped into four themes: Player, Match, Tournament, and Environment. Data was analysed using univariate and multivariate mixed-effects regression.

Results
Multi-variate regression identified that higher intensity match-play movement demands were associated with day 1, half 1, winning and/or drawing the match, closer score lines, playing in a top-5 ranked team, playing against opponents closer in the standings, starting the match, playing as a back or speed edge, being an international player, playing in warmer climates, and playing later in the day.

Conclusion
This study highlights how contextual factors can affect match-play movement demands in women’s rugby sevens. These findings can help coaches tailor training, optimise tactical decisions, and manage player workloads more effectively.

We examined the sweat characteristics and fluid balance of elite female field hockey players during two heat training camps. Fourteen elite female field hockey players from the Australian national squad participated in two heat training camps held ∼6 months apart, following winter- (Camp 1) and summer-based training (Camp 2). Daily waking body mass (BM) and urine specific gravity (USG) were collected, along with several markers of sweat and fluid balance across two matches per camp. There was a 19% mean reduction in estimated whole-body sweat sodium concentration from Camp 1 (45.8 ± 6.5 mmol/L) to Camp 2 (37.0 ± 5.0 mmol/L; p < .001). Waking urine specific gravity ≥ 1.020 was observed in 31% of samples, with no significant differences in mean urine specific gravity or BM between camps (p > .05), but with substantial interindividual variation. Intramatch sweat rates were high (1.2–1.8 L/hr), with greater BM losses in Camp 1 (p = .030), resulting in fewer players losing ≥2% BM in Camp 2 (0%–8%), as compared with Camp 1 (36%–43%; p = .017). Our field data suggest that elite female field hockey players experience substantial sweat losses during competition in the heat regardless of the season. In agreement with previous findings, we observed substantial interindividual variation in sweat and hydration indices, supporting the use of individualized athlete hydration strategies.

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.

The aim of this study was to examine the relationship between resting morning heart rate variability (HRV) metrics and indirect markers of hydration status in elite male athletes. Twenty-two field hockey players (age 26.8 ± 3.4 yr; height 178.4 ± 6.3 cm; body mass 76.2 ± 7.4 kg) were monitored over 10-d during a pre-Olympic training camp. Measurement of heart rate variability (HRV) during an orthostatic challenge, urine specific gravity (Usg, first morning void) and body mass were captured on seven of the mornings. Individual generalized linear mixed models evaluated the relationships between supine and standing HRV metrics with Usg and day-to-day change in body mass. No meaningful relationships were identified between supine (estimates −0.002 to 0.001) or standing (−0.002 to 0.003) HRV metrics and Usg as well as between supine (−0.003 to 0.016) or standing (−0.004 to 0.006) HRV metrics and changes in body mass. These outcomes indicate that supine and standing HRV metrics are not influenced by indirect indices of hydration status in elite male field hockey players.

Objectives

To characterize and compare match-play movement demands via Global Positioning Systems (GPS) between international and domestic women’s rugby sevens players performing in a novel elite dual-level tournament, with consideration to position and tournament characteristics.

Design

Fifty-four rugby sevens players; twenty-one international(5 speed edges, 8 backs, 8 forwards), and thirty-three domestic(10 speed edges, 11 backs, 12 forwards) wore GPS devices during an elite dual-level tournament covering 2 seasons, with 367 full match-play data files analysed. International and domestic players were distributed evenly between competing teams.

Methods

Match-play movement demands were characterized by distance, speed, and acceleration-based indices from 5 to 10 Hz GPS devices.

Results

International players recorded significantly higher high-intensity match-play movement demands compared to domestic players in distance in high and very high-speed zones (P = 0.01, P = 0.03, P = 0.01, P = 0.03), maximal acceleration (P = 0.001), maximal velocity (P < .001), speed exertion (P = 0.01),       , and acceleration load density (P = 0.03)   . Positional analysis demonstrated forwards displayed the largest significant differences between international and domestic players. . Total and relative match-play movement demands of the dual-level tournament also showed comparable demands to previous international tournament research.

Conclusions

Results identify key points of difference in match-play movement demands between player levels in women’s rugby sevens, and provides important information on the characteristics of playing positions, and of a dual-level tournament of this nature. This will improve the design and implementation of structures from domestic to international level.

Brosnan, RJ, Watson, G, Stuart, W, Twentyman, C, Kitic, CM, and Schmidt, M. The validity, reliability, and agreement of GPS units-Can we compare research and applied data? J Strength Cond Res 36(12): 3330-3338, 2022-This study's aim was to investigate the validity, within-brand interunit reliability, and between-brand agreement of movement indicators from 3 commonly used global positioning system (GPS) units used in applied and research settings. Forty-two units (GPSports EVO; 10 Hz, n = 13: GPSports HPU; 5 Hz, n = 14: and Catapult S5; 10 Hz, n = 15) were investigated across 3 experiments: a 40-m linear track with all units pushed on a trolley, a sport simulation circuit with all units pulled on a sled, and a similar circuit with 3 models of units placed in a modified GPS vest worn by an athlete between the scapulae. Distance, speed, and acceleration indices were obtained and analyzed with the level of significance set (rho < 0.05). The results demonstrated good to moderate (% mean difference; 0-6.5%) validity with criterion and good (coefficient of variation [CV] +/- 90% confidence interval [CI]: 0-3.9%) interunit reliability for distance and speed in units. Ten hertz units demonstrated good to moderate (CV +/- 90% CI: 0.21-5.58%) interunit reliability in all acceleration and deceleration measures, with 5 Hz units having good to poor (CV +/- 90% CI: 4.54-12.78%) results. Agreement ranged from good to moderate (% mean difference; 0.01-7.8%) for distance, speed, and absolute acceleration/deceleration. Agreement ranged from good to poor (% mean difference; 2.21-32.74%) in average acceleration. The GPS units investigated can be compared within and between applied and research settings for distance and speed. However, caution is warranted in acceleration indices. This highlights the importance of testing other commonly used GPS models and brands.

This study investigated whether heat acclimation (HA) could improve rowing performance in temperate conditions in national-level rowers. Using a parallel-group design, eleven rowers (3 female, 8 male, age: 21 +/- 3 years, height: 182.3 +/- 6.8cm, mass: 79.2 +/- 9.0kg, (V) over dotO(2peak): 61.4 +/- 5.1ml.kg.min(-1)) completed either a HA intervention (HEAT, n = 5) or acted as controls (CON, n = 6). The intervention replaced usual cross-training sessions and consisted of an hour of submaximal cycling or rowing ergometry in either 34 +/- 0 degrees C for HEAT or 14 +/- 1 degrees C for CON daily over two five-day blocks (10 sessions total), separated by 72h. Participants performed the '10+4' test that consists of 10-min submaximal rowing and a 4-min time-trial (TT) in temperate conditions (20 +/- 0 degrees C) before and after the intervention. Heat acclimation following the 10-session intervention was evidenced by large significant (p<0.05) decreases in maximum tympanic temperature (d = -1.68) and rate of perceived exertion (RPE) (d = -2.26), and a large significant increase in sweat loss (d = 0.91). Large non-significant (p>0.05) decreases were seen in average tympanic temperature (d = - 3.08) and average heart rate (d = -1.53) in HEAT from session 2 to session 10 of the intervention. Furthermore, a large significant increase was seen in plasma volume (d = 3.74), with large significant decreases in haemoglobin concentration (d = -1.78) and hematocrit (d = -12.9). Following the intervention, large non-significant increases in respiratory exchange ratio (d = 0.87) and blood lactate (d = 1.40) as well as a large non-significant decrease in RPE (d = -1.23) were seen in HEAT during the 10-min submaximal rowing. A large significant decrease in peak heart rate (d = -2.27), as well as a large non-significant decrease in relative (V) over dotO(2peak) (d = -0.90) and large non-significant increases in respiratory exchange ratio (d = 1.18), blood lactate concentration (d = 1.25) and power output (d = 0.96) were seen in HEAT during the 4-min TT. This study suggests that a 10-session HA intervention may elicit HA in national-level rowers, with potential to improve 4-min TT performance in temperate conditions.

Background: Despite a range of efforts to increase physical activity participation in Australia, inactivity levels in older adults have remained high over recent decades, contributing to increased rates of chronic health conditions. Lifestyle interventions, including telephone counseling (TC), improve physical activity participation and associated health outcomes over the short term; however, ongoing feedback and support is required to maintain these changes. Newer technologies such as wearable activity trackers (ATs) may offer an alternative method for providing ongoing support.

Objective: This study aims to investigate whether newer technologies such as wearable ATs assist in providing ongoing support to maintain physical activity levels and health outcomes.

Methods: Older adults aged >60 years who had just completed a 12-week face-to-face individualized community exercise program in Tasmania, Australia, participated in the study. They were randomized to receive AT, TC, or usual care (UC). All groups received a home exercise program and an optional referral to a community-based exercise program. The AT group also received an AT and text message feedback from an accredited exercise physiologist (AEP). The TC group received phone calls from an AEP throughout the 12-month intervention. The primary outcome was daily steps measured by an ActivPAL (TM) accelerometer at baseline and at 3, 6, and 12 months. Secondary outcome measures included body composition, blood pressure, 10-time sit-to-stand (TTSTS) test, timed up and go test, and cardiorespiratory fitness. This trial was approved by the Tasmanian Health and Medical Human Research Ethics Committee (H0014713).

Results: A total of 117 participants were randomized to the study (AT, n=37; TC, n=38; UC, n=42). At baseline, the participants (75/117, 64.1% female; mean age 72.4 years, SD 6.4) completed an average of 6136 steps (SD 2985) per day. Although there were no significant differences between groups, the TC and AT groups maintained daily step counts (mean difference [MD] -79 steps, 95% CI -823 to 663 steps; P=.81; and MD -588 steps, 95% CI -1359 to 182 steps; P=.09), and UC showed a reduction in daily steps (MD 981 steps, 95% CI -1668 to -294 steps; P=.003) during the 12-month period. Diastolic blood pressure was significantly higher after AT than after UC (MD 5.62 mm Hg, 95% CI 1.30 to 9.94 mm Hg; P=.01), and TTSTS was significantly slower on TC compared with UC (MD 2.36 seconds, 95% CI -0.14 to 4.87 seconds; P=.03).

Conclusions: The use of an AT with AEP support or TC is effective at maintaining daily step count in older adults over a 12-month period, suggesting that wearable ATs are as effective as TC. Further research to investigate which option is more cost-effective would be beneficial.

Strenuous exercise increases gastrointestinal damage, but the dose-response relationship is yet to be elucidated. It is also commonly believed that running causes greater gastrointestinal damage than cycling. Two randomised, crossover studies aimed to 1) quantify gastrointestinal damage with increasing exercise intensity, and 2) determine if running was associated with greater gastrointestinal damage than cycling. Following a maximal oxygen uptake (V̇O2max) test, participants completed 3 cycling trials at different intensities (60 min at 40%, 60% and 80% V̇O2max; n = 10 (5 female, 5 male)) (INTENSITY), or 1 running and 1 cycling trial (45 min at 70% V̇O2max; n = 11 (3 female, 8 male)) (MODE). Venous blood samples were collected pre- and post-exercise to measure gastrointestinal damage via intestinal fatty acid binding protein (I-FABP). In INTENSITY, I-FABP magnitude of change was greater at 80% V̇O2max than 40% V̇O2max (p < 0.01). In MODE, I-FABP magnitude of change was greater with cycling (mean (SD)) (84.7 (133.2)% d = 1.07) compared with running (19.3 (33.1)%, d = 0.65) with a moderate effect (d = 0.68, p = 0.024). Rating of perceived exertion (RPE) and heart rate (HR) were higher during cycling (RPE p < 0.0001; HR p < 0.0001) but rectal temperature was not different between modes (p = 0.94). While gastrointestinal damage increases with increasing exercise intensity, running was not associated with greater gastrointestinal damage than cycling. Novelty: A fraction of the anaerobic threshold, rather than a fraction of V̇O2max, may be more predictive of intensity that results in exercise induced gastrointestinal damage. The mode of exercise may not be as important as intensity for inducing gastrointestinal damage. Improving anaerobic threshold may reduce susceptibility to gastrointestinal damage when exercising at high intensities.