Ben J. Dascombe

Exercise with Blood Flow Restriction: An Updated Evidence-Based Approach for Enhanced Muscular Development

A growing body of evidence supports the use of moderate blood flow restriction (BFR) combined with low-load resistance exercise to enhance hypertrophic and strength responses in skeletal muscle. Research also suggests that BFR during low-workload aerobic exercise can result in small but significant morphological and strength gains, and BFR alone may attenuate atrophy during periods of unloading. While BFR appears to be beneficial for both clinical and athletic cohorts, there is currently no common consensus amongst scientists and practitioners regarding the best practice for implementing BFR methods. If BFR is not employed appropriately, there is a risk of injury to the participant. It is also important to understand how variations in the cuff application can affect the physiological responses and subsequent adaptation to BFR training. The optimal way to manipulate acute exercise variables, such as exercise type, load, volume, inter-set rest periods and training frequency, must also be considered prior to designing a BFR training programme. The purpose of this review is to provide an evidence-based approach to implementing BFR exercise. These guidelines could be useful for practitioners using BFR training in either clinical or athletic settings, or for researchers in the design of future studies investigating BFR exercise.

A comparison of the activity demands of elite and sub-elite Australian men's basketball competition

Abstract The purpose of the study was to describe the differences in the activity demands of sub-elite and elite Australian mens basketball competition. Ten elite (age 28.3 ± 4.9 years, mass 97.0 ± 13.9 kg, height 197.4 ± 8.3 cm) and 12 sub-elite (age 26.1 ± 5.3 years, mass 85.9 ± 13.2 kg, height 191.4 ± 7.6 cm) Australian basketball players participated in the study. Player activity was analysed using video-based time–motion analysis across multiple in-season matches. Customized analytical software was used to calculate player activity into frequencies, mean and total durations (s), and mean and total distances (m) for standing/walking, jogging, running, sprinting, low shuffling, high shuffling, and dribbling movements. Only movement frequency was calculated for jumping and upper body activity. Multivariate analysis of variance revealed that elite players performed significantly more total movement changes (P <0.001), and experienced greater activity workloads while jogging (P <0.01) and running (P <0.002). In contrast, sub-elite players performed significantly more standing/walking (P <0.023) and sprinting (P <0.003) activities. These data suggest that elite basketball competition requires a greater intermittent workload and more sustained activity demands, whereas sub-elite competition may involve greater bursts of activity and longer recovery periods. These differences are likely to reflect variations in player skill and fitness, as well as playing structure between playing standards.

The physiological and activity demands experienced by Australian female basketball players during competition

OBJECTIVES To describe the physiological and activity demands experienced by Australian female basketball players during competition. DESIGN A between-subjects (positional comparison) repeated measures (playing periods) observational experimental design was followed. METHODS State-level basketball players (n=12; age: 22.0±3.7 yr; body mass: 72.9±14.2 kg; stature: 174.2±6.9 cm; body fat: 17.2±5.6%; estimated V˙O(2max):43.3±5.7 ml  kg⁻¹ min⁻¹) volunteered to participate. Heart rate (HR) and blood lactate concentration ([BLa]) were collected across eight competitive matches. Overall and positional player activity demands were calculated across three matches using time-motion analysis methodology. Activity frequencies, total durations and total distances were determined for various activity categories. RESULTS Mean (±SD) HR responses of 162±3b min⁻¹ (82.4±1.3% HR(max)) and 136±6b min⁻¹ (68.6±3.1% HR(max)) were evident across live and total time during matches. A mean [BLa] of 3.7±1.4 mmol L⁻¹ was observed across competition. Player activity demands were unchanged across match periods, with 1752±186 movements performed and 5214±315 m travelled across total live match time. Furthermore, 39±3%, 52±2%, 5±1% and 4±1% of total live time was spent performing low-intensity, moderate-intensity, high-intensity and dribbling activity. Positional comparisons revealed backcourt players performed more ball dribbling (p<0.001) and less standing/walking (p<0.01) and running (p<0.05) than frontcourt players. CONCLUSIONS Together, these findings highlight the high intermittent demands and important contributions of both anaerobic and aerobic metabolic pathways during state-level female basketball competition.

The Impact of Different Environmental Conditions on Cognitive Function: A Focused Review.

Cognitive function defines performance in objective tasks that require conscious mental effort. Extreme environments, namely heat, hypoxia, and cold can all alter human cognitive function due to a variety of psychological and/or biological processes. The aims of this Focused Review were to discuss; (1) the current state of knowledge on the effects of heat, hypoxic and cold stress on cognitive function, (2) the potential mechanisms underpinning these alterations, and (3) plausible interventions that may maintain cognitive function upon exposure to each of these environmental stressors. The available evidence suggests that the effects of heat, hypoxia, and cold stress on cognitive function are both task and severity dependent. Complex tasks are particularly vulnerable to extreme heat stress, whereas both simple and complex task performance appear to be vulnerable at even at moderate altitudes. Cold stress also appears to negatively impact both simple and complex task performance, however, the research in this area is sparse in comparison to heat and hypoxia. In summary, this focused review provides updated knowledge regarding the effects of extreme environmental stressors on cognitive function and their biological underpinnings. Tyrosine supplementation may help individuals maintain cognitive function in very hot, hypoxic, and/or cold conditions. However, more research is needed to clarify these and other postulated interventions.

Ice slurry ingestion during cycling improves Olympic distance triathlon performance in the heat

Abstract This study investigated the effect of ice slurry ingestion during a triathlon on intragastric temperature and 10 km running performance in the heat. Nine well-trained male triathletes performed two randomised trials of a simulated Olympic distance triathlon in hot conditions (32–34°C). Exercise intensity during the swim (1500 m) and cycle (1 hr) legs was standardised, and the 10 km run leg was a self-paced time trial. During the cycle leg, either 10 g · kgBM−1 of ice slurry (< 1°C) or room temperature fluid (32–34°C) was ingested. In the run leg of the ice slurry trial, performance time (43.4 ± 3.7 vs. 44.6 ± 4.0 min; P = 0.03), intragastric temperature (at 1.5 km; 35.5 ± 1.2 vs. 37.5 ± 0.4°C; P = 0.002) and perceived thermal stress (at 5 km; 73 ± 9 vs. 80 ± 7 mm; P = 0.04) were significantly lower. Oxygen consumption was significantly higher in the ice trial between 9.5–10 km (52.4 ± 3.4 vs. 47.8 ± 5.4 mL · kg−1 · min−1; P = 0.04). The results suggest ice slurry ingestion was an effective ergogenic aid for triathlon running performance in the heat. The attenuation of intragastric temperature and perceived thermal stress were likely contributors to the self-selection of a higher running intensity and improved performance time.

Effect of N-acetylcysteine on cycling performance after intensified training.

PURPOSE This investigation examined the ergogenic effect of short-term oral N-acetylcysteine (NAC) supplementation and the associated changes in redox balance and inflammation during intense training. METHODS A double-blind randomized placebo-controlled crossover design was used to assess 9 d of oral NAC supplementation (1200 mg·d) in 10 well-trained triathletes. For each supplement trial (NAC and placebo), baseline venous blood and urine samples were taken, and a presupplementation cycle ergometer race simulation was performed. After the loading period, further samples were collected preexercise, postexercise, and 2 and 24 h after the postsupplementation cycle ergometer race simulation. Changes in total antioxidant capacity, ferric reducing ability of plasma, reduced glutathione, oxidized glutathione, thiobarbituric acid-reactive substances, interleukin 6, xanthine oxidase, hypoxanthine, monocyte chemotactic protein 1, nuclear factor κB, and urinary 15-isoprostane F2t concentration were assessed. The experimental procedure was repeated with the remaining supplement after a 3-wk washout. Eight participants completed both supplementation trials. RESULTS NAC improved sprint performance during the cycle ergometer race simulation (P < 0.001, ηp = 0.03). Supplementation with NAC also augmented postexercise plasma total antioxidant capacity (P = 0.005, ηp = 0.19), reduced exercise-induced oxidative damage (plasma thiobarbituric acid-reactive substances, P = 0.002, ηp = 0.22; urinary 15-isoprostane F2t concentration, P = 0.010, ηp = 0.431), attenuated inflammation (plasma interleukin 6, P = 0.002, ηp = 0.22; monocyte chemotactic protein 1, P = 0.012, ηp = 0.17), and increased postexercise nuclear factor κB activity (P < 0.001, ηp = 0.21). CONCLUSION Oral NAC supplementation improved cycling performance via an improved redox balance and promoted adaptive processes in well-trained athletes undergoing strenuous physical training.

Training Monitoring for Resistance Exercise: Theory and Applications

Resistance exercise is difficult to quantify owing to its inherent complexity with numerous training variables contributing to the training dose (type of exercise, load lifted, training volume, inter-set rest periods, and repetition velocity). In addition, the intensity of resistance training is often inadequately determined as the relative load lifted (% 1-repetition maximum), which does not account for the effects of inter-set recovery periods, repetition velocity, or the number of repetitions performed in each set at a given load. Methods to calculate the volume load associated with resistance training, as well as the perceived intensity of individual sets and entire training sessions have been shown to provide useful information regarding the actual training stimulus. In addition, questionnaires to subjectively assess how athletes are coping with the stressors of training and portable technologies to quantify performance variables such as concentric velocity may also be valuable. However, while several methods have been proposed to quantify resistance training, there is not yet a consensus regarding how these methods can be best implemented and integrated to complement each other. Therefore, the purpose of this review is to provide practical information for strength coaches to highlight effective methods to assess resistance training, and how they can be integrated into a comprehensive monitoring program.

Blood flow restricted exercise for athletes: A review of available evidence.

OBJECTIVES This study aimed to collate current evidence regarding the efficacy of various blood flow restriction (BFR) strategies for well-trained athletes, and to provide insight regarding how such strategies can be used by these populations. DESIGN Review article. METHODS Studies that had investigated the acute or adaptive responses to BFR interventions in athletic participants were identified from searches in MEDLINE (PubMed), SPORTDiscus (EBSCO) and Google Scholar databases up to April 2015. The reference lists of identified papers were also examined for relevant studies. RESULTS Twelve papers were identified from 11 separate investigations that had assessed acute and adaptive responses to BFR in athletic cohorts. Of these, 7 papers observed enhanced hypertrophic and/or strength responses and 2 reported alterations in the acute responses to low-load resistance exercise when combined with BFR. One paper had examined the adaptive responses to moderate-load resistance training with BFR, 1 noted improved training responses to low-work rate BFR cardiovascular exercise, and 1 reported on a case of injury following BFR exercise in an athlete. CONCLUSIONS Current evidence suggests that low-load resistance training with BFR can enhance muscle hypertrophy and strength in well-trained athletes, who would not normally benefit from using light loads. For healthy athletes, low-load BFR resistance training performed in conjunction with normal high-load training may provide an additional stimulus for muscular development. As low-load BFR resistance exercise does not appear to cause measureable muscle damage, supplementing normal high-load training using this novel strategy may elicit beneficial muscular responses in healthy athletes.

No effect of upper body compression garments in elite flat-water kayakers

Abstract While the effect of lower body compression garments on performance and physiological responses are well documented, no studies have examined the effect of upper body compression garments (UBCG) on upper-body dominant exercise. This study examined the effects of wearing UBCG on performance and physiological responses during simulated flat-water kayaking. Five male (mean values±s: 21.8±2.8 years; 83.5±9.2 kg; 63.0±5.5 ml·kg−1·min−1) and two female (mean values±s: 25.0±4.2 years; 71.4±2.7 kg; 51.0±4.8 ml·kg-1·min-1) elite flat-water kayakers completed a six-step incremental test followed by a four-minute maximal performance test (4minPT) in both UBCG and control (no shirt or sports training bra) conditions in a randomized counter-balanced order. Heart rate and oxygen consumption (O2) as well as performance measures (power, distance covered, stroke rate) were recorded during the tests, and blood lactate was measured immediately after each incremental step and three minutes following the 4minPT. Near-infrared spectroscopy-derived measures of blood flow and oxygenation of the flexor carpi radialis were monitored continuously for all tests. No significant differences between the UBCG and control conditions were evident for any performance, cardiorespiratory or oxygenation measure across the incremental step test and 4minPT. It was concluded that wearing UBCG did not provide any significant physiological or performance benefits during simulated flat-water kayaking.

Cooling During Exercise: An Overlooked Strategy for Enhancing Endurance Performance in the Heat

It is well established that endurance performance is negatively affected by environmental heat stress due to a complex interaction of physical, physiological and psychological alterations. Numerous scientific investigations have attempted to improve performance in the heat with pre-cooling (cooling prior to an exercise test), and as such this has become a well-established ergogenic practice for endurance athletes. However, the use of mid-cooling (cooling during an exercise test) has received considerably less research attention in comparison, despite recent evidence to suggest that the advantage gained from mid-cooling may outweigh that of pre-cooling. A range of mid-cooling strategies are beneficial for endurance performance in the heat, including the ingestion of cold fluids and ice slurry, both with and without menthol, as well as cooling of the neck and face region via a cooling collar or water poured on the head and face. The combination of pre-cooling and mid-cooling has also been effective, but few comparisons exist between the timing and type of such interventions. Therefore, athletes should experiment with a range of suitable mid-cooling strategies for their event during mock competition scenarios, with the aim to determine their individual tolerable limits and performance benefits. Based on current evidence, the effect of mid-cooling on core temperature appears largely irrelevant to any subsequent performance improvements, while cardiovascular, skin temperature, central nervous system function and psychophysiological factors are likely involved. Research is lacking on elite athletes, and as such it is currently unclear how this population may benefit from mid-cooling.