Melissa Crowe

EFFECTS OF SIX WEEKS OF β-HYDROXY-β-METHYLBUTYRATE (HMB) AND HMB/CREATINE SUPPLEMENTATION ON STRENGTH, POWER, AND ANTHROPOMETRY OF HIGHLY TRAINED ATHLETES

This study investigated the effects of 6 weeks of dietary supplementation of β-hydroxy-β-methylbutyrate (HMB) and HMB combined with creatine monohydrate (HMBCr) on the muscular strength and endurance, leg power, and anthropometry of elite male rugby league players. The subjects were divided into a control group (n = 8), a HMB group (n = 11; 3 g·d-1)or a HMBCr group (n = 11; 12 g·d-1 with 3 g HMB, 3 g Cr, 6 g carbohydrates). Three repetition maximum lifts on bench press, deadlifts, prone row, and shoulder press, maximum chin-up repetitions, 10-second maximal cycle test, body mass, girths, and sum of skinfolds were assessed pre-and postsupplementation. Statistical analysis revealed no effect of HMB or HMBCr on any parameter compared with presupplementation measures or the control group. HMB and HMBCr were concluded to have no ergogenic effect on muscular strength and endurance, leg power, or anthropometry when taken orally by highly trained male athletes over 6 weeks.

Understanding factors that influence participation in physical activity among people with a neuromusculoskeletal condition: a review of qualitative studies

Abstract Purpose: This review aims to describe the factors that influence participation in physical activity (PA) in people with neuromusculoskeletal (NMS) conditions. Methods: A systematic search of six databases was conducted. Articles were included if the study qualitatively explored factors that influence participation in PA by individuals with a NMS condition. Fifteen peer-reviewed articles published between 2003 and 2013 were analysed for common themes and critically appraised. Results: Results were categorised using the International Classification of Functioning, Disability and Health framework. The most common demotivators reported for the three areas of functioning, body function and structures, activities and participation were lack of walking balance, muscle weakness, pain, stiffness, bladder and blower problems, depression, thermoregulation and fear of injury. Fluctuating symptoms and fatigue were mentioned as demotivators in all of the progressive conditions. Maintaining independence, function and weight, and the prevention of secondary conditions were the leading motivators reported in this domain. Most common environmental barriers include accessibility, costs, transport and insufficient information and knowledge from health professionals. Social support is a consistent determinate of PA and is reported as a facilitator in every study. The most common personal demotivators include lack of motivation, feelings of self-consciousness and embarrassment in public, anxiety, frustration and anger. Personal motivators include goal setting and achieving, enjoyment, feeling good, feeling “normal”, motivation and optimism, redefining self and escapism from everyday boundaries. Conclusions: Individuals with NMS conditions report complex common barriers, facilitators, demotivators and motivators to participation in PA. The way these factors influence participation in PA is unique to the individual; therefore, it is necessary to adopt an individually tailored approach when designing interventions. Implications for Rehabilitation Individuals with neuromusculoskeletal conditions report common factors that influence participation in physical activity. It is the characteristics, attitude and beliefs of an individual that determine the way in which these factors influence participation in physical activity. Health professionals should be guided by the International Classification of Functioning, Disability and Health framework when assessing individuals, as the model will ensure all major factors of interest with regard to disability and physical activity behaviour are considered. Interventions to promote participation in physical activity in people with neuromusculoskeletal conditions require an individual approach that facilitates the assessment and management of an individual’s barriers to physical activity. A multi-disciplinary approach may be required to address factors that influence participation in physical activity. Health professionals must be informed about other areas of expertise and draw on this when necessary.

Eye Colour and Reaction Time to Visual Stimuli in Rugby League Players

Subjects with dark eye colour are thought to perform better on reactive tasks in comparison to light-eyed subjects, whereas light-eyed subjects show enhanced performance over dark-eyed subjects on self-paced activities. This study examined reaction time using unrestricted and peripheral vision and success at the self-paced activity of goal kicking in 59 elite male Rugby League players. Subjects with dark eye colour did not react significantly faster than the light-eyed subjects when tested using unrestricted vision or peripheral vision. Examination of the self-paced activity of goal kicking showed that the percentage success rate was not significantly higher in the light-eyed group than the dark-eyed group. In conclusion, there was no significant difference in reaction time to a visual stimulus or success in goal kicking between dark- and light-eyed Rugby League players.

Nicotine effects on exercise performance and physiological responses in nicotine‐naïve individuals: a systematic review

The purpose of this systematic review was to evaluate the effects of smokeless forms of nicotine on physiological responses and exercise performance. Methodology and reporting were based on the PRISMA statement. The intervention was defined as any product containing nicotine that did not require smoking. Searches were conducted across two electronic databases with supplementary approaches utilized. Studies were selected following set inclusion and exclusion criteria and checked by two independent authors. A modified PEDro scale was utilized to rate study quality with studies averaging 9·3/13. Six studies assessed exercise performance with endurance‐based parameters reported as significantly improved with nicotine in one study, while anaerobic parameters were unaffected or decreased compared to placebo except in one study which reported enhanced leg extensor torque but no effect on countermovement jump or Wingate anaerobic capacity. Sixteen of 28 studies investigating physiological responses reported that nicotine significantly increased heart rate compared to placebo or control. Blood pressure and blood flow were also reported as significantly increased in multiple studies. While there is strong evidence of nicotine‐induced changes in physiological function that would benefit physical performance, beneficial effects have only been reported on leg extensor torque and endurance performance by one study each. Subsequently, there is need for more research with strong methodological quality to definitively evaluate nicotines potential as an ergogenic aid.

Team sport athletes’ perceptions and use of recovery strategies: a mixed-methods survey study

BackgroundA variety of recovery strategies are used by athletes, although there is currently no research that investigates perceptions and usage of recovery by different competition levels of team sport athletes.MethodsThe recovery techniques used by team sport athletes of different competition levels was investigated by survey. Specifically this study investigated if, when, why and how the following recovery strategies were used: active land-based recovery (ALB), active water-based recovery (AWB), stretching (STR), cold water immersion (CWI) and contrast water therapy (CWT).ResultsThree hundred and thirty-one athletes were surveyed. Fifty-seven percent were found to utilise one or more recovery strategies. Stretching was rated the most effective recovery strategy (4.4/5) with ALB considered the least effective by its users (3.6/5). The water immersion strategies were considered effective/ineffective mainly due to psychological reasons; in contrast STR and ALB were considered to be effective/ineffective mainly due to physical reasons.ConclusionsThis study demonstrates that athletes may not be aware of the specific effects that a recovery strategy has upon their physical recovery and thus athlete and coach recovery education is encouraged. This study also provides new information on the prevalence of different recovery strategies and contextual information that may be useful to inform best practice among coaches and athletes.

Physiological, Biochemical, and Psychological Responses to Environmental Survival Training in the Royal Australian Air Force

Military environmental survival training (EST) is designed and considered to evoke significant stressors to military personnel in preparation for combat-like scenarios. The aim of this study was to observe and report selected physiological, biochemical, psychological, and performance responses to this intense 15-day program of Royal Australian Air Force (RAAF) EST. Fourteen RAAF participants undertook the EST course. Physiological and psychological responses were collected across the 15 days across outcomes: (1) biochemical markers (blood lactate, interlukin-6, and creatine kinase), (2) performance and anthropometric indices (vertical jump, body mass), and (3) psychological questionnaires profile of mood states, depression anxiety stress scale, Kessler-10 etc.). Creatine kinase concentration increased significantly from baseline to day 5 (p < 0.05) and thereafter remained elevated for the remaining 10 days of EST (128%; p < 0.01). Vertical jump (-10%; p < 0.01) and body mass (-8%; p < 0.01) both decreased across 15 days of EST, while there were no significant change in interlukin-6. Negative psychological responses were observed for mood (p < 0.01), depression (p < 0.05), anxiety (p < 0.01), and stress (p < 0.01) following the EST course. This case study showed the RAAF EST course imposed significant physiological and psychological stress as observed from markers of muscle damage, deterioration in physical performance, substantial weight loss, negative mood, and psychological distress.

Anthropometry and the Response to Dietary Supplementation in Exercise

A high proportion of athletes consume dietary supplements in the belief that they will enhance performance or alter body composition. Therefore, research into dietary supplements should accurately evaluate alterations in body composition, specifically muscle and fat mass (FM). A number of factors need to be considered in the selection of anthropometric methodologies to evaluate body composition changes due to dietary supplementation. These factors include measurement details (reliability, validity, accuracy and sensitivity), ethical factors such as invasiveness, statistical effect size and practical considerations such as time, cost and equipment availability. Researchers should first consider the statistical effect size of the supplement under study. Does previous research indicate a marked effect of the supplement on body composition? If so, then a less sensitive methodology can be utilised. Where previous research indicates only a small or negligible effect on body composition, the more sensitive anthropometric methodologies should be employed. The validity and reliability of the anthropometric technique is important. However, there is a lack of research into the reliability and validity of various anthropometric methodologies when assessed in conjunction with dietary supplementation. Examination of recent research into the most popular dietary supplements including creatine monohydrate, β-hydroxy-β-methyl butyrate (HMB), chromium picolinate, Tribulus Terrestris, ephedrine and L-carnitine, reveals utilisation of a wide variety of anthropometric methodologies with no particular methodology associated with detecting significant effects on body composition. Ephedrine, when combined with caffeine, and creatine are amongst the few dietary supplements consistently reported to alter body composition. Changes in hydration status can lead to confounding errors when assessing body composition and researchers should aim to minimise or control alterations in hydration status. Future research is needed in the area of anthropometry and dietary supplementation, particularly investigating the validity and reliability of various anthropometric techniques to detect change in body composition as a result of dietary supplementation. A greater availability of this information would assist researchers to choose appropriate anthropometric methodology to assess the effects of dietary supplements on muscle and FM.

Heart rate variability during rest and exercise in various environmental conditions

The beat-to-beat variation in time between heart beats is known as heart rate variability (HRV). The effect that temperature and humidity have on this function of heart rate (HR) control remains largely unclear. Therefore, the current study examined the effects of different environmental conditions on HRV during rest and moderate exercise. Seven healthy male volunteers (age 20.6, range 19 - 23 yrs) participated in the study. Participants completed the protocol under four environmental conditions in randomised order within a climate control chamber. These conditions were: thermoneutral (TN; 20°C, 50% relative humidity [rh]), cold/dry (CD; 5°C, 35% rh), hot/dry (HD; 40°C, 35% rh) and hot/humid (HH; 32°C, 75% rh). Variables were recorded during supine rest, sitting and treadmill exercise of 50% maximum TN HR. Two-way repeated measures ANOVA (p<0.05) showed VO2, ventilation and RPE were significantly higher during rest compared to exercise but there was no effect of condition. RER was significantly higher in TN and CD compared to HH. Exercise and condition had no effect on core temperature. Thermal discomfort was significantly higher in CD compared to the other conditions. Skin temperatures (head, arm, back, chest) were significantly higher in HH and HD compared to CD with chest and back being significantly lower in CD compared to TN. Hot/dry conditions resulted in significantly greater HR and reduced HRV compared to CD. In the current study, HD induced greater central and peripheral cardiovascular stress compared with CD despite greater thermal discomfort in CD.