Eric J. Jones

Warm-Up and Stretching in the Prevention of Muscular Injury

Muscular injury is one of the major problems facing today’s athletes, both recreational and professional. Injuries to skeletal muscle represent >30% of the injuries seen in sports medicine clinics. As a result, it is imperative to utilise the most effective means to aid in deterring these injuries. However, there are conflicting opinions regarding methods of reducing muscular injury through warm-up and stretching techniques.Therefore, the purpose of this article is to examine the potential of a warm-up and/or stretching routine in deterring muscular injury during physical activity. The article examines a variety of studies regarding warm-up, stretching and muscular injury. The article also provides a definition of warm-up and stretching to provide clarity on this topic. Many of the differences within previous research were due to conflicting definitions. We also address this issue by examining research on muscular injury and physical adaptations to muscular injury and training.This article provides contradictory evidence to conclusions that have been drawn in previous review articles, which determined that warm-up and/or stretching protocols did not deter injury. The research included here conveys that certain techniques and protocols have shown a positive outcome on deterring injuries. As a result, a warm-up and stretching protocol should be implemented prior to physical activity. The routine should allow the stretching protocol to occur within the 15 minutes immediately prior to the activity in order to receive the most benefit. In addition, current information regarding improvements in flexibility is reviewed.

Recovery From Training: A Brief Review: Brief Review

Athletes spend a much greater proportion of their time recovering than they do in training. Yet, much attention has been given to training with very little investigation of recovery. The purpose of this review is to stimulate further research into this vital area of training. Recovery can be categorized in three terms: i) immediate recovery between exertions; ii) short-term recovery between repeats (e.g., between resistance sets or interval bouts); and iii) training recovery between workouts. The focus of this review is training recovery. Full training recovery is essential to optimal performance and improvement. This review includes an examination of extant research on recovery and a very brief review of some potential modalities and techniques for hastening recovery and the time course of recovery and responses to some treatments. Measures of recovery and practical considerations are discussed briefly. Much research is needed in this area, but there are obstacles to high quality research. Attention must be given to key issues in research on recovery, especially the individual response to recovery treatments.

Cross-sectional area and muscular strength: a brief review.

A brief review is provided on the relationship of strength to muscle crosssectional area (CSA). It is commonly believed that maximal force and CSA are strongly related. Studies examining varying levels of training status display discordant data suggesting complex relationships between training status, CSA and peak force. It has been reported that trained participants had a significantly larger force to CSA ratio (F/CSA) than untrained males and females. Therefore, it is difficult to attribute all force changes due to training to CSA changes. In general, studies of CSA and strength suggest that sex differences may exist. For example, recreationally trained female weightlifters produced higher F/CSA than males at lower velocities of contraction. Definitive conclusions regarding sex differences, force production and CSA are difficult because of limited studies and equivocal results among these studies. Some studies have also examined the impact of aging on F/CSA. These studies seem to follow the same pattern as studies on sex differences and training status, with data suggesting that F/CSA varies unpredictably across ages and that differences may be attributed to factors other than age alone. In the papers reviewed, the relationship between force and CSA is neither consistent nor simple. Although some of the discrepancies between studies could be attributed to methodological variations, this does not seem likely to explain all differences. The F/CSA relationship seems complex, and future studies are required to elucidate the relationships among key factors in the expression of strength.

Stability of a practical measure of recovery from resistance training.

McLester et al. (2003) proposed a practical protocol to determine optimal recovery times between resistance training workouts. For this protocol to be useful, it must be stable. The purpose of this study was to investigate the stability of that protocol. College-aged resistance trained men (n = 10) performed 3 sets to volitional failure using a 10-repetition maximum load for 6 exercises. Recovery was evaluated on 4 occasions by the number of repetitions performed for each individual exercise after recovery periods of 48, 72, 96, and 120 hours in counterbalanced order. To evaluate stability, this procedure was performed twice. The number of repetitions after each recovery interval were compared with initial baseline performances. A priori, adequate stability was defined as 70% of the participants achieving similar recovery duration on both trials. Pooled repetitions over all 6 exercises indicated that 80% of participants returned to baseline strength levels after the same recovery duration for both trials. However, when individual muscle group repetition performance was evaluated, stability varied from 20 to 70%. Variability in rest, nutrition, prior activity, and other factors probably induced instability in individual strength measures, but not sufficiently to influence the aggregate results. Some muscle groups may have greater sensitivity to variations in ecological factors such as these. We believe that the tested protocol may be useful in establishing recovery times for multimuscle group workouts, but not stable enough to be useful in establishing recovery times for individual muscle groups.

Continuous versus Episodic Hydration in Encapsulating Protective Coveralls

Work in warm environments while wearing respiratory protective masks can result in progressive dehydration. The purpose of this study was to evaluate the use of a portable hands-free, through-the-gas mask hydration system on workers in encapsulating protective coveralls (EPC) in the heat. Ten participants performed four trials of simulated “moderate” intensity industrial work (300 Kcal/min) at a wet bulb glove temperature WBGT of 23°C while wearing impermeable (two trials) and semipermeable (two trials) EPC. Participants performed the trials under two conditions: (1) drinking ad libitum from a portable hands-free system (PHFS) using a through-the-gas mask drinking device, and (2) using typical rest-only, wherein participants worked until a termination criterion was met, then were removed from the work environment and permitted to drink as much as they desired. When using the PHFS, for the impermeable EPC trial, participants drank 242% of what they drank during the drinking-during-rest trial. Total work times were unchanged between trials for either condition, but there was a trend for walk time to be longer in PHFS for semipermeable EPC. Dehydration with PHFS was only 21% (dehydration was 4.7 times greater without the PHFS) in impermeable EPC and in semipermeable EPC only 41% of that without hydration available (dehydration was 2.5 times greater without the PHFS). Under these conditions, hypohydration was effectively mitigated using the portable system.

Approach, avoidance and weight-related testing: An investigation of frontal EEG asymmetry.

Two motivational systems underlie behaviour and affective responses – an inhibition/avoidance system and an activation/approach system. The purpose of the present study was to explore if individual differences in these motivational systems would occur in response to common weight and body composition testing within a sample of young, adult women. Electroencephalogram was used to distinguish approach or avoidance orientations via frontal asymmetry before and after testing sessions. Clear distinctions in motivational response were found, with 65% of the sample responding with an approach motivation, while 35% responded with an avoidance motivation. Even though all participants, on average, experienced a negative affective response, only the avoidance group self-reported a subsequent increase in “comfort food” consumption of desserts and snacks the week following the testing session. As shown with other stressors, clear individual differences exist in motivational responses to common weight and body composition testing. Such testing produces a general negative affective response; however, the individual differences in motivational responses might produce different behavioural choices. Future research and interventions in health communication should be considerate to this variation in motivational responses to help explain changes in both healthy and unhealthy behaviours following interactions involving one’s body weight and/or body composition.

Establishing the Learned Effect of Repeated Wingate Anaerobic Tests: 774 Board #170 May 27, 2

The Wingate anaerobic test (WAnT) is a recognized and well-established measure of power output, muscular endurance, and fatigue. However, a learning effect could reduce the reliability of these measures. PURPOSE: To establish the number of WAnT trials needed to produce a learned effect. METHODS: Thirty-six apparently healthy college-aged men (n=20) and women (n=16) who had not previously performed a WAnT participated in five WAnT trials separated by a minimum of 72 hours. Peak Power (PP) and Mean Power (MP) were recorded for each trial. Resistance for trials was calculated at 7.5% of each respective participant’s weight. RESULTS: In men, paired samples t-test revealed PP increased on all trials (2-5) when compared to trial 1 (+44.66W, +49.19W, +55.80W, +63.95W; p=0.02, p=0.01, p=0.01, p=0.00, respectively). PP significantly increased from trial 1 to trial 2 (849.21±127.41 watts to 893.87±143.92 watts, p .05). The same results were found for MP, with a significant increase from trial 1 to 2 (627.90±79.01 watts to 660.04±79.66 watts, p .05). There was a trend toward an elicited peak MP at trial 3 (p=.09, Cohen’s d= -.83). In women, the average PP and MP for trial 1 was 547.74±94.56 watts and 415.91±68.21 watts, respectively, with no significant differences found between trials (p>.05). These results suggest that a learned effect is present within PP and MP until trial 2 of the WAnT, with a trend toward peak MP at trial 3 for male participants. CONCLUSION: Thereby, suggesting that when performing WAnT, utilizing less than 3 practice trials might elicit significant power increase in male participants due to this learned effect. Current data suggests that female participants elicit peak power at trial 1 of the WAnT, with no significant increase in subsequent trials. Additional research should be conducted in order to further investigate the non-significant trend of increasing power output across WAnT trials in male participants as well the lack of female learned response.

Recreational deer hunting tree stand injuries in the USA: A brief review

Almost 11 million people are estimated to be recreational deer hunters in the USA. This review summarizes current knowledge regarding tree stand injuries associated with deer hunting, a popular outdoor recreational activity in the USA. Injuries from falling from tree stands now represent a greater threat to hunters than firearms injuries. Reported injury rates, when sufficient information was provided, varied from 0.002 to 0.053. One of the most commonly reported injuries was to the spinal cord. Contributing accident factors were: mechanical failures, use of intoxicants, failure to use a fall arrest device, falling asleep, and carelessness. Ascending and descending from the stand were found to be particularly hazardous. Better record keeping and improved outdoor education might improve the safety of this outdoor activity.