Mechanisms underlying the health benefits of intermittent hypoxia conditioning.

Intermittent hypoxia (IH) is commonly associated with pathological conditions, particularly obstructive sleep apnoea. However, IH is also increasingly used to enhance health and performance and is emerging as a potent non-pharmacological intervention against numerous diseases. Whether IH is detrimental or beneficial for health is largely determined by the intensity, duration, number and frequency of the hypoxic exposures and by the specific responses they engender. Adaptive responses to hypoxia protect from future hypoxic or ischaemic insults, improve cellular resilience and functions, and boost mental and physical performance. The cellular and systemic mechanisms producing these benefits are highly complex, and the failure of different components can shift long-term adaptation to maladaptation and the development of pathologies. Rather than discussing in detail the well-characterized individual responses and adaptations to IH, we here aim to summarize and integrate hypoxia-activated mechanisms into a holistic picture of the body's adaptive responses to hypoxia and specifically IH, and demonstrate how these mechanisms might be mobilized for their health benefits while minimizing the risks of hypoxia exposure.

The effects of taurine ingestion on anaerobic and physiological performance in female rugby players.

The purpose of this study was to investigate the acute effect of low, moderate, or high doses of taurine on anaerobic and physiological performance in female rugby players. A total of 16 sub-elite female rugby athletes (21.3 ± 1.5 yr, 168.0 ± 4.9 cm, 62.1 ± 3.5 kg mean ± SD) participated in this research. Following familiarization, participants attended 4 successive tests separated by 72 h in a randomized, counter-balanced, crossover research design. Following an over night fast, participants completed a 5-min 60 Watt warm-up followed by a 30-s Wingate anaerobic test on a cycle ergometer after ingestion of either 2 g taurine (LOWTAU), 4 g (MODTAU), 6 g (HIGHTAU) or placebo (PLA) 1 h before the test. Peak (PP) and mean power (MP) along with heart rate (HR), rating of perceived exertion (RPE), capillary lactate and blood glucose were measured. LOWTAU did not affect PP, MP, HR, lactate and glucose compared to PLA (p > 0.05), while MODTAU improved MP and HIGHTAU improved PP and MP compared to PLA and LOWTAU (p < 0.05). MODTAU and HIGHTAU had little effect on HR, blood lactate and glucose (p > 0.05). A single dose of taurine (MODTAU or HIGHTAU) 1 h prior to competition or training would provide an ergogenic effect on subsequent power output.

Effects of whole body vibration exercise combined with weighted vest in older adults: a randomized controlled trial.

BACKGROUND: To evaluate the training effects of whole body vibration (WBV) combined with weighted vest (WV) in older adults. METHODS: This randomized controlled trial study was conducted in healthy older adults living in the community. Fifty-one participants were randomly allocated into 3 groups: group 1 (n = 17), WBV alone, training on WBV at a frequency 30 Hz, amplitude 2 mm, 10 sets of 1 min squats, with 60 s rest, group 2 (n = 15), WV alone, squat exercise, 10 sets of 1 min, with 60 s rest, while WV loaded with 10% body weight and group 3 (n = 19), WBV + WV, combining WBV exercise with the addition of a WV. All groups completed training 3 times per week for 8 weeks. The outcomes were total muscle mass, muscle thickness, maximal isometric strength, single-leg-stance and timed-up-and-go evaluated at baseline and after training. RESULTS: As a result of training all groups improved their isometric muscle strength with little difference between groups. The single-leg-stance significantly improved only in WBV + WV group 25.1 ± 10.8 s (mean ± 95% CI, p < 0.01). The timed-up-and-go improved in all groups, but the improvement was significantly greater in the WBV + WV group (17.5 ± 6.9%) compared to the WV (8.5 ± 3.2%) and WBV groups (9.2 ± 5.4%, p = 0.043, 0.023 respectively). Rectus femoris muscle thickness and total muscle mass were significantly increased in all groups equally with little difference between groups. CONCLUSION: The combined WBV + WV had a greater effect on the single-leg-stance and the timed-up-and-go compared to WV or WBV alone. TRIAL REGISTRATION: TCTR20190306001. Thai Clinical Trials Registry ( www.thaiclinicaltrials.org ). Date of registration: 6 March 2019.

Profiling the tackle and its injury characteristics in premier New Zealand club rugby union players over a complete season.

OBJECTIVES: RugbySmart is a safe tackle technique education programme. Our objective was to identify whether the RugbySmart-recommended safe tackle technique was exhibited by club rugby players and whether tackle-related injuries showed poor tackle technique characteristics. METHODS: The prospective cohort design enabled 28 senior club based amateur male rugby union players from New Zealand to be followed over 18 matches in the 2017 rugby season. Game video analysis by three analysts provided categorisation of tackle technique into type, approach, foot contact, leading foot and rear foot position, face and head position. Injuries were diagnosed by the same sports medicine physician. RESULTS: In the 18 matches, 28 players completed a combined total of 3006 tackles, with only six tackle-related injuries sustained. Notable findings included: (1) forwards complete more tackles than backs; (2) shoulder tackles were the most prevalent tackle; (3) good tackle technique as promoted by RugbySmart was demonstrated in 57.9% of all tackles and (4) of the six tackle-related injuries, two occurred despite RugbySmart desired tackle techniques. CONCLUSION: This is the first study to investigate whether players were performing the recommended 'safe tackle technique' proposed by New Zealand Rugby's RugbySmart programme. As two of six tackle-related injuries occurred despite the RugbySmart preferred technique being performed, further technique analysis and a larger sample are needed to determine what techniques reduce risk of injury during tackles. As only 57.9% of tackles were performed with RugbySmart head and foot positions, further research and education regarding tackle technique recommendations are needed.

Plyometric Training in Normobaric Hypoxia improves Jump Performance.

Strength training in hypoxia has been shown to enhance hypertrophy and function of skeletal muscle, however, the effects of plyometric training in hypoxia is relatively unknown. Therefore, this study aimed to examine the effects of plyometric training in hypoxia compared to normoxia on body composition, sprint and jump parameters. Twenty-three male physical education students (20.4±2.0 years, mean±SD) participated in the study and were divided into a plyometric training in hypoxia (PTH, n=8), plyometric training in normoxia (PTN, n=7) or control group (C, n=8). The PTH group trained in normobaric hypoxia (approximately 3536 m) 3 days/week for 8 weeks, while the PTN trained in normoxia. PTH induced significant improvements from baseline to post-testing in countermovement-jump (37.8±6.7 cm, 43.4±5.0 cm, p<0.05), squat-jump (35.4±6.2 cm, 41.1±5.7 cm, p<0.05), drop-jump height (32.8±6 cm, 38.1±6 cm, p<0.05) and 20-m sprint performance (3257.1±109.5 ms, 3145.8±83.6 ms, p<0.05); whereas PTN produced significant improvement only in countermovement-jump (37.3±4.8 cm, 40.5±4.5 cm, p<0.05) and 20-m sprint performance (3209.: 3±76.1 ms, 3126.6±100.4 ms, p<0.05). Plyometric training under hypoxic conditions induces greater improvement in some jump measures (drop-jump and squat-jump) compared to similar training in normoxia.

Running Demands of Provincial Women's Rugby Union Matches in New Zealand.

ABSTRACT: Busbridge, AR, Hamlin, MJ, Jowsey, JA, Vanner, MH, and Olsen, PD. Running demands of provincial women's rugby union matches in New Zealand. J Strength Cond Res 36(4): 1059-1063, 2022-There has been rapid growth in participation in women's rugby but there is minimal research on the sport. The aim of this study was to increase our knowledge of the running demands of high-level female players in the New Zealand Provincial Rugby Competition. Players (n = 20) wore 10-Hz Global Positioning System units during 7 matches to measure total distance covered, all running distance (≥6.4 km·h-1), high-intensity (HI) running (≥16.1 km·h-1), meters per minute (m·min-1), and maximum speed (km·h-1). Mean ± SD were calculated for forwards and backs. Forwards and backs covered a similar total distance (5,616 ± 809 m and 5,852 ± 1,022 m, respectively) and running distance (3,181 ± 583 m and 3,095 ± 805 m, respectively). However, when separated into specific playing positions, the half back recorded significantly higher running distances (4,292 ± 171 m), greater HI running distances (1,003 ± 58 m), and more distance overall (6,812 ± 277 m) than other positions (p ≤ 0.05). By contrast, outside backs did less running (2,456 ± 114 m) than other positions (p ≤ 0.05), and had the lowest distance for HI running (528 ± 39 m) in the backs. Running demands were similar for forwards and backs; however, within positions there was considerable variation, and the lower running measurements for outside backs maybe unique to women's rugby. Due to these findings and possible different tactical approaches, the development of training and speed zone bands specific to female players is advised because male research findings may lack transferability to women's rugby.

Senior Club-Level Rugby Union Player's Positional Movement Performance Using Individualized Velocity Thresholds and Accelerometer-Derived Impacts in Matches.

ABSTRACT: Takamori, S, Hamlin, MJ, Kieser, DC, King, D, Hume, P, Yamazaki, T, Hachiya, M, and Olsen, PD. Senior club-level rugby union player's positional movement performance using individualized velocity thresholds and accelerometer-derived impacts in matches. J Strength Cond Res 36(3): 710-716, 2022-Game demands of professional rugby union players have been well documented; however, there is minimal game demand information using individualized velocity thresholds and collision loads, particularly for amateurs. This study investigated movement patterns of 20 male amateur rugby players during 16 senior premier division one matches using global positioning system (GPS) devices sampling at 10 Hz. Derived GPS variables included distances, velocities, sprinting, and impacts. Data files from 86 player games (≥60 minutes of play per game) were categorized into broad (forwards and backs) and specific (front row, second row, back row, half back, inside back, and outside back) positional groups for analysis. It was most likely that backs covered more distance in the high-speed running (>60% maximal velocity) zone (502 ± 157 m) compared with forwards (238 ± 147 m) (100/0/0%, chances of positive/trivial/negative differences, effect size [ES] = 1.3), performed more striding (backs 1,116 ± 240, forwards 954 ± 240 m, 96/4/0%, ES = 0.5), and sprinting (backs 121 ± 58, forwards 90 ± 65 m, 93/7/0%, ES = 0.5). However, forwards had higher collision loads (35 ± 12 arbitrary units) compared with backs (20 ± 6, 99.9/0.1/0%, ES = 1.3) with back row forwards completing the highest collision load of any playing position (40 ± 13). Our example match movement performance and impact information is valuable to coaches and support staff in preparing player profiles for similar-level rugby players to help manage their workloads.

Short and long-term differences in anthropometric characteristics and physical performance between male rugby players that became professional or remained amateur.

OBJECTIVE: The objective of this study was to investigate which anthropometric and physical performance variables characterised players that advanced to professional teams (professionals) and how these variables changed over time, compared to those that did not secure professional contracts (i.e. remained amateurs). METHODS: Differences in anthropometry, strength, speed, power and intermittent running ability in 83 male rugby players collected between 2015 and 2019 were determined using repeated measures analysis. RESULTS: When arriving for the first year of the program, forwards that went on to become professional players were older (0.4 ± 0.3 yr, mean ± 95% CI, p = 0.004), heavier (4.6 ± 2.5 kg, p < 0.001) and stronger (range 6.2-16.4%) than forwards that remained amateur. Professional forwards were also slower at sprinting (range -2.7-2.9%, p < 0.001) and had lower Yo-Yo IRT L1 (-10.8%, p = 0.03). When first arrived on the program, professional backs were taller (3.5 ± 1.8 cm, p < 0.001), heavier (4.6 ± 2.4 kg, p < 0.001) and faster over 20 m (-1.9 ± 1.7%, p = 0.03) and 30 m (-1.7 ± 1.6%, p = 0.04) compared to amateurs. Compared to amateurs, professionals had a smaller increase in body mass (-4.2 ± 2.0%, p < 0.001) and greater improvement in sprinting (3.7, 2.8, 2.8% over 10, 20 and 30-m, respectively) and Yo-Yo IRT L1 (14.7 ± 11.0%, p = 0.05) over 3 years training. CONCLUSION: Characteristics that are likely to assist players in becoming professionals include being older, heavier, taller and stronger.

Fitness and Fatness Are Both Associated with Cardiometabolic Risk in Preadolescents.

OBJECTIVE: To determine the associations between cardiorespiratory fitness (CRF) and fatness (overweight-obesity) with cardiometabolic disease risk among preadolescent children. STUDY DESIGN: This cross-sectional study recruited 392 children (50% female, 8-10 years of age). Overweight-obesity was classified according to 2007 World Health Organization criteria for body mass index. High CRF was categorized as a maximum oxygen uptake, determined using a shuttle run test, exceeding 35 mL·kg-1·minute-1 in girls and 42 mL·kg-1·minute-1 in boys. Eleven traditional and novel cardiometabolic risk factors were measured including lipids, glucose, glycated hemoglobin, peripheral and central blood pressure, and arterial wave reflection. Factor analysis identified underlying cardiometabolic disease risk factors and a cardiometabolic disease risk summary score. Two-way analysis of covariance determined the associations between CRF and fatness with cardiometabolic disease risk factors. RESULTS: Factor analysis revealed four underlying factors: blood pressure, cholesterol, vascular health, and carbohydrate-metabolism. Only CRF was significantly (P = .001) associated with the blood pressure factor. Only fatness associated with vascular health (P = .010) and carbohydrate metabolism (P = .005) factors. For the cardiometabolic disease risk summary score, there was an interaction effect. High CRF was associated with decreased cardiometabolic disease risk in overweight-obese but not normal weight children (P = .006). Conversely, high fatness was associated with increased cardiometabolic disease risk in low fit but not high fit children (P < .001). CONCLUSIONS: In preadolescent children, CRF and fatness explain different components of cardiometabolic disease risk. However, high CRF may moderate the relationship between fatness and cardiometabolic disease risk. TRIAL REGISTRATION: ACTRN 12614000433606.

Hypoxic training improves blood pressure, nitric oxide and hypoxia-inducible factor-1 alpha in hypertensive patients.

PURPOSE: To examine the effects of intermittent hypoxic breathing at rest (IHR) or during exercise (IHT) on blood pressure and nitric oxide metabolites (NOx) and hypoxia-inducible factor-1 alpha levels (HIF-1α) over a 6-week period. METHODS: 47 hypertensive patients were randomly allocated to three groups: hypertensive control (CON: n = 17; IHR: n = 15 and IHT: n = 15. The CON received no intervention; whereas, IH groups received eight events of hypoxia (FIO2 0.14), and normoxia (FIO2 0.21), 24-min hypoxia and 24-min normoxia, for 6 weeks. The baseline data were collected 2 days before the intervention; while, the post-test data were collected at days 2 and 28 after the 6-week intervention. RESULTS: We observed a significant decrease of the SBP in both IH groups: IHR (- 12.0 ± 8.0 mmHg, p = 0.004 and - 9.9 ± 8.8 mmHg, p = 0.028, mean ± 95% CI) and IHT (- 13.0 ± 7.8 mmHg, p = 0.002 and - 10.0 ± 8.4 mmHg, p = 0.016) at days 2 and 28 post-intervention, respectively. Compared to CON, IHR and IHT had increased of NOx (IHR; 8.5 ± 7.6 µmol/L, p = 0.031 and IHT; 20.0 ± 9.1 µmol/L, p < 0.001) and HIF-1α (IHR; 170.0 ± 100.0 pg/mL, p = 0.002 and IHT; 340.5 ± 160.0 pg/mL, p < 0.001). At 2 days post-intervention, NOx and HIF-1α were negatively correlated with SBP in IHT. CONCLUSION: IH programs may act as an alternative therapeutic strategy for hypertension patients probably through elevation of NOx and HIF-1α production.