Live high-train low altitude training: responders and non-responders

Objective: Investigate differences between athletes that responded (improved performance) compared to those that did not, after a 20-day “live high-train low” (LHTL) altitude training camp. Methods: Ten elite triathletes completed 20 days of live high (1545-1650 m), train low (300 m) training. The athletes underwent (i), two 800-m swimming time trials at sea-level (1 week prior to and 1 week after the altitude camp) and (ii) two 10-min standardised submaximal cycling tests at altitude on day 1 and day 20 of the altitude camp. Acute mountain sickness (AMS) was also measured during the camp. Based on their 800-m swimming time trial performances, athletes were divided into responders (improved by 3.2 ± 2.2%, mean ± SD, n=6) and non-responders (decreased by 1.8 ± 1.2%, n=4). Results: Compared to non-responders, the responders had lower exercise heart rates (-6.3 ± 7.8%, mean ± 90% CL, and higher oxygen saturations (1.2 ± 1.3%) at the end of the 10-min submaximal test after the camp. Compared to the responders, the non-responders had substantially higher VE and VE/VO₂ during the submaximal test on day 1 of the altitude training camp, and a substantially higher RER during the submaximal test on day 20 of the camp. As a result of the altitude training, exercise economy of the non-responders compared to the responders deteriorated (i.e., non-responders required more oxygen per watt). Non-responders were 3.0 times (90% CL=0.5-16.6) more likely to suffer symptoms of acute mountain sickness during first 5 days of altitude compared to responders. Conclusion: Changes in SpO₂, heart rate and some respiratory variables during exercise and resting AMS scores may help determine athletes that respond to LHTL altitude training camps from athletes that fail to respond to such training

The effect of intermittent hypoxic training on performance

This study aimed to verify whether the “live low, train high” approach is beneficial for endurance and/or anaerobic cycling performance. Sixteen well-trained athletes completed 90 min of endurance training (60-70% of heart rate reserve) followed by two 30-s all-out sprints (Wingate test), daily for 10 consecutive days. Nine subjects (IHT group) trained with an F₁O₂ set to produce arterial oxygen saturations of ~88% to ~82%, while 7 subjects (placebo group) trained while breathing a normal gas mixture (F₁O₂ = 0.21). Four performance tests were conducted at sea-level including a familiarisation and baseline trial, followed by repeat trials at 2 and 9 days post-intervention. Relative to the placebo group mean power during the 30-s Wingate test increased by 3.0% (95% Confidence Limits, CL ± 3.5%) 2 days, and 1.7% (± 3.8%) 9 days post-IHT. Changes in other performance variables (30-s peak power, 20-km mean power, 20-km oxygen cost) were unclear. During the time trial the IHT participants‟ blood lactate concentration, RER and SpO₂ relative to the placebo group, was substantially increased at 2 days post-intervention. The addition of IHT into the normal training programme of well-trained athletes produced worthwhile gains in 30-s sprint performance possibly through enhanced glycolysis.Lincoln University Research Fund, Sport and Recreation New Zealan

Running demands in New Zealand club, semi-professional and professional rugby union competitions

Game demands of professional rugby players are well documented, however, there is minimal research on the running demands in amateur and semi-professional competitions. To the authors knowledge, no research has compared the running demands in club, national (division 1 (NPC) and division 2 (Heartland)) or international provincial (Super rugby) competitions. Information on the running demands of each competition would enable trainers to develop training programs specific to player’s needs and assist in the transition of players between competitions. Players from a team in each competition level wore a 10 Hz GPS unit during all games in a rugby season. Total distance (m), running distance (≥7 km.h-1(m)) and high intensity running (≥16 km.h-1(m)) were recorded. The research was approved by an Institutional Ethics Board and the NZ Rugby Union. Lower competition (club and division 2) players covered greater distances (150m to 400m) per game than higher level players. As in total distance, division 2 players ran (≥7 km.h-1) more in games (120m) compared to higher level players. However, club players typically covered less running distance than higher level players (3102m vs 3237 to 3319m, p=0.10 to 0.00). In contrast, Super rugby players typically ran greater distances (962m) at higher speeds (≥16 km.h-1) per game. This information could assist in the development of competition-specific training programs, and the monitoring of training loads during a season and when a player returns from an injury. Further analysis will investigate running demands of rugby positions in each competition to enable the development of position-specific-training programs

Associations between physical activity and stress levels in medical doctors working in New Zealand and Australia during initial COVID-19 restrictions

In 2020, the world was gripped by the COVID-19 pandemic which put an unprecedented strain on health care workers. The aim of this study was to assess the effects of the Australian and New Zealand lockdowns on physical activity, depression, and anxiety in medical doctors. We hypothesized that during stressful times such as the COVID-19 pandemic lockdown, physical activity would have a positive effect on the mental health of medical doctors. Convenience sampling (using mass emailing via professional networks including medical associations) and snowball sampling were used during the early period of COVID-19 government mandated restrictions (25 March to 27 April 2020) in New Zealand and Australia. All registered medical doctors working in New Zealand and Australia were eligible to participate in the survey. The short survey collected information demographics, levels of physical activity and mental health using the International Physical Activity Questionnaire: Short Form and the Depression, Anxiety and Stress Scale-42. Of 469 participants who completed the survey, over 81% met the recommended physical activity levels (150 minutes of at least moderate-intensity physical activity/week). Physically inactive New Zealand and Australian medical doctors reported significantly higher depression (p = 0.006), anxiety (p = 0.008) and stress (p = 0.002) scores compared to their active counterparts. This study demonstrated that less physical activity was associated with higher anxiety and depression in medical doctors. A key recommendation from this study is to incorporate greater access to physical activity in healthcare settings for medical doctors

Hypoxic repeat sprint training improves rugby player's repeated sprint but not endurance performance

This study aims to investigate the performance changes in 19 well-trained male rugby players after repeat-sprint training (six sessions of four sets of 5 × 5 s sprints with 25 s and 5 min of active recovery between reps and sets, respectively) in either normobaric hypoxia (HYP; n = 9; F₁O₂ = 14.5%) or normobaric normoxia (NORM; n = 10; F₁O₂ = 20.9%). Three weeks after the intervention, 2 additional repeat-sprint training sessions in hypoxia (F₁O₂ = 14.5%) was investigated in both groups to gauge the efficacy of using "top-up" sessions for previously hypoxic-trained subjects and whether a small hypoxic dose would be beneficial for the previously normoxic-trained group. Repeated sprint (8 × 20 m) and Yo-Yo Intermittent Recovery Level 1 (YYIR1) performances were tested twice at baseline (Pre 1 and Pre 2) and weekly after (Post 1-3) the initial intervention (intervention 1) and again weekly after the second "top-up" intervention (Post 4-5). After each training set, heart rate, oxygen saturation, and rate of perceived exertion were recorded. Compared to baseline (mean of Pre 1 and Pre 2), both the hypoxic and normoxic groups similarly lowered fatigue over the 8 sprints 1 week after the intervention (Post 1: -1.8 ± 1.6%, -1.5 ± 1.4%, mean change ± 90% CI in HYP and NORM groups, respectively). However, from Post 2 onwards, only the hypoxic group maintained the performance improvement compared to baseline (Post 2: -2.1 ± 1.8%, Post 3: -2.3 ± 1.7%, Post 4: -1.9 ± 1.8%, and Post 5: -1.2 ± 1.7%). Compared to the normoxic group, the hypoxic group was likely to have substantially less fatigue at Post 3-5 (-2.0 ± 2.4%, -2.2 ± 2.4%, -1.6 ± 2.4% Post 3, Post 4, Post 5, respectively). YYIR1 performances improved throughout the recovery period in both groups (13-37% compared to baseline) with unclear differences found between groups. The addition of two sessions of "top-up" training after intervention 1, had little effect on either group. Repeat-sprint training in hypoxia for six sessions increases repeat sprint ability but not YYIR1 performance in well-trained rugby players

Measurement of cardiorespiratory fitness in children from two commonly used field tests after accounting for body fatness and maturity

Body fat and maturation both influence cardiorespiratory fitness, however few studies have taken these variables into account when using field tests to predict children's fitness levels. The purpose of this study was to determine the relationship between two field tests of cardiorespiratory fitness (20 m Maximal Multistage Shuttle Run [20-MST], 550 m distance run [550-m]) and direct measurement of VO2max after adjustment for body fatness and maturity levels. Fifty-three participants (25 boys, 28 girls, age 10.6 ± 1.2 y, mean ± SD) had their body fat levels estimated using bioelectrical impedance (16.6% ± 6.0% and 20.0% ± 5.8% for boys and girls, respectively). Participants performed in random order, the 20-MST and 550-m run followed by a progressive treadmill test to exhaustion during which gas exchange measures were taken. Pearson correlation coefficient analysis revealed that the participants' performance in the 20-MST and 550-m run were highly correlated to VO2 max obtained during the treadmill test to exhaustion (r = 0.70 and 0.59 for 20-MST and 550-m run, respectively). Adjusting for body fatness and maturity levels in a multivariate regression analysis increased the associations between the field tests and VO2max (r = 0.73 for 20-MST and 0.65 for 550-m). We may conclude that both the 20-MST and the 550-m distance run are valid field tests of cardiorespiratory fitness in New Zealand 8-13 year old children and incorporating body fatness and maturity levels explains an additional 5-7% of the variance. © Editorial Committee of Journal of Human Kinetics

Integrity of chromatin and replicating DNA in nuclei released from fission yeast by semi-automated grinding in liquid nitrogen

<p>Abstract</p> <p>Background</p> <p>Studies of nuclear function in many organisms, especially those with tough cell walls, are limited by lack of availability of simple, economical methods for large-scale preparation of clean, undamaged nuclei.</p> <p>Findings</p> <p>Here we present a useful method for nuclear isolation from the important model organism, the fission yeast, <it>Schizosaccharomyces pombe</it>. To preserve <it>in vivo </it>molecular configurations, we flash-froze the yeast cells in liquid nitrogen. Then we broke their tough cell walls, without damaging their nuclei, by grinding in a precision-controlled motorized mortar-and-pestle apparatus. The cryo-ground cells were resuspended and thawed in a buffer designed to preserve nuclear morphology, and the nuclei were enriched by differential centrifugation. The washed nuclei were free from contaminating nucleases and have proven well-suited as starting material for genome-wide chromatin analysis and for preparation of fragile DNA replication intermediates.</p> <p>Conclusions</p> <p>We have developed a simple, reproducible, economical procedure for large-scale preparation of endogenous-nuclease-free, morphologically intact nuclei from fission yeast. With appropriate modifications, this procedure may well prove useful for isolation of nuclei from other organisms with, or without, tough cell walls.</p

Does intermittent hypoxic exposure enhance the cardioprotective effect of exercise in an inactive population?

The aim of this study was to determine whether exercise supplemented with passive intermittent hypoxic exposure (IHE) improved overall cardiovascular disease risk and individual risk factors. Participants were randomized to exercise-only (Ex, n = 18, 5 males, 13 females; age: 56.4 ± 6.5 years; weight: 81.2 ± 15.9; height: 167.3 ± 8.42) or exercise + IHE (IHE + Ex, n = 16; 6 males, 10 females; age: 56.7 ± 6.4 years; weight: 78.6 ± 12.4 kg; height: 168.0 ± 8.8 cm). Both groups received the same strength and aerobic exercise training (1 h, 3 days/wk, 10 weeks). IHE + Ex also received IHE (5 min hypoxia: 5 min ambient air ×6) for 2–3 days/wk. Measurements were collected before (Baseline), after (Post), and 4- and 8-week following the intervention. There were small, beneficial reductions in overall 5- year cardiovascular risk in both groups. At Post, for IHE + Ex compared to IHE there were unclear to likely improvements in high density lipoprotein (8.0% ± 8.0%), systolic blood pressure (−3.4% ± 3.4%) and VO₂peak (3.1% ± 7.7%). These improvements persisted at 8-week. There was an unclear improvement in arterial wave reflection (augmentation index) at Post (−6.1% ± 18.4%, unclear), but became very likely harmful at 8-week (8-week: 24.8% ± 19.7%). The conflicting findings indicate that in inactive adults, the addition of IHE to exercise may be beneficial to systemic markers of cardiovascular health but may also increase myocardial load due to increased arterial wave reflection