Phil J. Handcock

The New Zealand rugby injury and performance project. III. Anthropometric and physical performance characteristics of players.

OBJECTIVE: To investigate the anthropometric and physical performance characteristics of New Zealand rugby players of different ages and both sexes. METHODS: 356 rugby players (264 male, 92 female) took part in the study during a single season. Playing grade ranged from schoolboys and schoolgirls to senior men and women. Assessment of height, weight, neck circumference, and somatotype was performed before the competitive rugby season. A battery of six physical performance assessments was completed after the anthropometry. Analysis of variance was used to examine differences in these variables between field positions and grades. RESULTS: Significant differences between forwards and backs on anthropometric and physical performance variables were apparent at all grades assessed. In terms of anthropometric characteristics, forwards of a given grade were generally taller, possessed greater body mass, and were more endomorphic and less ectomorphic than backs of the same grade. The backs tended to perform better on physical performance measures than forwards, being more aerobically fit, faster, more agile, and possessing a higher degree of muscular endurance. Differences in anthropometry and physical performance attributes were also apparent between players from the various grades. The players at higher levels were generally larger, and performed better on tests of physical performance than the players at lower levels. These differences were found in both sexes. CONCLUSIONS: The greater body mass of the forwards allows them to obtain greater momentum than the backs when sprinting. The ability to obtain greater momentum is important in the body contact phases of the game. Forwards may compromise their aerobic fitness and speed to some extent in order to maintain a high body mass. The anthropometric and physical performance characteristics of players appear to reflect the demands placed on them by the sport.

Impact of police body armour and equipment on mobility

Body armour is used widely by law enforcement and other agencies but has received mixed reviews. This study examined the influence of stab resistant body armour (SRBA) and mandated accessories on physiological responses to, and the performance of, simulated mobility tasks. Fifty-two males (37 ± 9.2 yr, 180.7 ± 6.1 cm, 90.2 ± 11.6 kg, VO2max 50 ± 8.5 ml kg(-1) min(-1), BMI 27.6 ± 3.1, mean ± SD) completed a running VO2max test and task familiarisation. Two experimental sessions were completed (≥4 days in between) in a randomised counterbalanced order, one while wearing SRBA and appointments (loaded) and one without additional load (unloaded). During each session participants performed five mobility tasks: a balance task, an acceleration task that simulated exiting a vehicle, chin-ups, a grappling task, and a manoeuvrability task. A 5-min treadmill run (zero-incline at 13 km·h(-1), running start) was then completed. One min after the run the five mobility tasks were repeated. There was a significant decrease in performance during all tasks with loading (p < 0.001). Participants were off-balance longer; slower to complete the acceleration, grapple and mobility tasks; completed fewer chin-ups; and had greater physiological cost (↑ %HRmax, ↑ %VO2max, ↑ RER) and perceptual effort (↑ RPE) during the 5-min run. Mean performance decreases ranged from 13 to 42% while loaded, with further decreases of 6-16% noted after the 5-min run. Unloaded task performance was no different between phases. Wearing SRBA and appointments significantly reduced mobility during key task elements and resulted in greater physiological effort. These findings could have consequences for optimal function in the working environment and therefore officer and public safety.

Does exercise evoke neurological symptoms in healthy subjects

Concussion is a common injury in collision sports and is evidenced by a variety of signs and symptoms. The recording of neurological symptoms is an important component of screening for a concussion and in return-to-play decisions. However similar symptoms are prevalent in the general population and are reported to be associated with participation in physical activities. The purpose of this study was to document the neurological symptoms reported by healthy individuals following controlled bouts of exercise. A crossover randomised design with 2 levels of exercise intensity, moderate intensity and high intensity, each of 15min duration was used. Participants completed a standardised postconcussion symptom checklist prior to exercise (pre), immediately following exercise (post-1) and again after 15 min of rest (post-2). 60 participants were recruited into the study. A summed symptom score was calculated and analysed with a 2-way repeated measures ANOVA procedure. The intensityxtime interaction (F(2,118)=23.94, p<0.001) demonstrated a significant increase in symptom scores for the high intensity condition immediately following exercise (p<0.001). Although the moderate intensity showed a similar trend this was not significant. These findings suggest that sports medicine professionals need to be aware of the effect of exercise on symptom reporting when assessing and in making return-to-play decisions.

Sports concussion assessment: the effect of exercise on dynamic and static balance

This study determined the effect of exercise on measures of static and dynamic balance used in the assessment of sports‐related concussion (SRC). A balanced three‐group cross‐over randomized design was used with three levels of exercise verified by blood‐lactate, heart rate and “perceived‐exertion”: no exercise/rest (NE), moderate‐intensity exercise (ME), and high‐intensity exercise (HE). Participants performed two timed balance tasks: tandem gait (TG) and single‐leg stance (SLS); pre‐ and post‐exercise and 15 min after exercise. Linear mixed‐models with adjusted means and contrasts compared exercise effects. Ninety asymptomatic participants (45♂:45♀) were recruited. When times were contrasted with NE; HE resulted in a significant decrease in SLS (P<0.001) and TG (P<0.001) performance immediately following exercise. Fifteen minutes of recovery improved SLS (P<0.001) and TG (P=0.011) from post‐exercise performance. ME caused a significant decrease in performance in SLS (P=0.038) but not TG (P=0.428). No statistically significant change occurred following ME in any tasks after 15‐min recovery (SLS P=0.064; TG P=0.495). Test–retest reliability was considerably higher for the dynamic task compared with the static task. The reliability of static and dynamic balance tasks, and the change in performance following exercise, have implications for the immediate assessment of SRC, as these measures are utilized in concussion assessment instruments.

Body armour: the effect of load, exercise and distraction on landing forces

Abstract We investigated the effect of added load and intense exercise on jump and landing performance and ground reaction force (GRF) during landings where attentional demand was varied. Fifty-two males (37 ± 9.2 years, 180.7 ± 6.1 cm, 90.2 ± 11.6 kg, maximal aerobic fitness (V˙O2max) 50 ± 8.5 ml . kg−1 . min−1, BMI 27.6 ± 3.1, mean ± s) completed a V˙O2max test. Experimental sessions were completed (≥4 days in between) in a randomised counterbalanced order, one while wearing body armour and appointments (loaded) and one without load (unloaded). A vertical jump, a drop landing concentrating on safe touchdown, a drop jump and a drop landing with an attentional distraction were performed. These were repeated 1 min after a 5-min treadmill run. Mean jump height decreased by 12% (P < 0.001) with loading and a further by 6% following the running task. Peak GRFs were increased by 13–19% with loading (P < 0.001) depending on the landing task demands and a further by 4–9% following intense exercise. The distracted drop landing had significantly higher GRFs compared to all other landings. Results demonstrate that added load impacts on jumping and landing performance, an effect that is amplified by prior intense exercise, and distraction during landing. Such increases in GRF apply to police officer performance in their duties and may increase the risk of injury.

Changes in the timed finger-to-nose task performance following exercise of different intensities

Objective The purpose of this study was to determine the effect of different levels of exercise intensity on the timed finger-to-nose (FTN) task, a measure of upper limb coordination included in the Sport Concussion Assessment Tool (SCAT2). Methods A three-group crossover randomised design was used to investigate changes in FTN times at three levels of exercise intensity; no exercise/rest (NE), moderate intensity exercise (ME) and high-intensity exercise (HE). Heart rates and a rating of perceived exertion (Borg Scale) were recorded to verify the level of exercise intensity. Participants performed three trials of the timed FTN task: pre-exercise, post-exercise and 15 min after the cessation of exercise. Linear mixed models were used to compare FTN change scores associated with exercise. Results Ninety asymptomatic participants (45♂:45♀) aged 18–32 years completed the study. Changes in FTN scores from pre-exercise showed that the HE condition was facilitated relative to NE at post-exercise (8% faster, 95% CI 5% to 10%, p<0.001) and at post-15 (3% faster, 95% CI 1% to 6%, p=0.005). ME did not show such a facilitation following exercise (2% faster, 95% CI 0% to 4%, p=0.081 and 1% faster, 95% CI 1% to 4%, p=0.225 respectively). Conclusions Performance on the FTN task is enhanced by a short period of HE, and this effect persists for at least 15 min. There was no evidence of such an effect with ME.

No clear benefit of muscle heating on hypertrophy and strength with resistance training

ABSTRACT Heat is a major stressor during exercise, though its value in driving adaptation is not well understood. Muscle heating can upregulate pathways facilitating protein synthesis and could thereby enhance effects of exercise training, however, few studies have investigated this possibility. We examined whether heating active muscle during resistance training differentially affected physical and functional adaptations. Within a randomised contralateral-limb control study, ten healthy, resistance-untrained individuals (21 ± 3 y; 5 female) completed 30 sessions of progressive resistance training (12 weeks), performing 4 × 8 unilateral knee extensions at 70% of 1RM. One randomly-allocated thigh was heated during, and for 20 min after, each session using an electric pad eliciting muscle temperatures of >38 °C (HOT); the contralateral limb remained unheated (CON). Training intensity was progressed using 4-weekly strength assessments. Quadricep lean mass (measured using DXA) increased by 15 ± 7% in HOT (p = 0.00) and 15 ± 6% in CON (p = 0.00); the difference being trivial (p = 0.94). Peak isokinetic torque at 90°.s−1 increased by 30 ± 25% (HOT; p = 0.00) and 34 ± 33% (CON; p = 0.01), with no difference (p = 0.84) between limbs. Rate of torque development increased ∼40%, with no difference between limbs (p = 0.73). The increase in 3-RM strength was also similar in HOT (75 ± 16%) and CON (71 ± 14%; p = 0.80 for difference). No differences in mass or strength changes were evident between sexes. In conclusion, supplemental heating of active muscle during and after each bout of resistance training showed no clear positive (or negative) effect on training-induced hypertrophy or function.

Blue card: referees’ perspectives of a rugby union concussion recognition and management programme

Objective The Northland (New Zealand) Rugby Union developed an innovative concussion recognition and management programme (Blue Card) as part of its player welfare responsibilities for club (community) players. The referee is empowered to issue a Blue Card (BC) to any player they suspect of being concussed, thus removing them from the game. The purpose of this descriptive study was to investigate the referees’ perspectives on having this added responsibility, and whether this detracted from their enjoyment of refereeing. Design Cross-sectional survey. Setting Northland Rugby Union headquarters Participants Twenty-one amateur male referees who officiated in club-level rugby matches covered by the Northland Rugby Union Blue (NRUBC) programme during the 2014 season volunteered to participate. Outcome measures Custom-designed survey instrument using both open and closed questions. Main results The referees had between 2 and 35 (mean=12.1) seasons of refereeing experience with 81% (17/21) claiming a good or average knowledge of concussion. The majority (20/21) reported that they had sufficient training for their expanded role. Two thirds (14/21) of the respondents did not think that the additional responsibility impacted on their refereeing satisfaction. Over the season nine (9) BCs were issued by 7 of the participating referees, with 5 indicating that they were “very confident” in their decision. Conclusions The referees indicated that they were well prepared to handle the added responsibility as on-field concussion gatekeepers, and this role did not detract from their enjoyment of refereeing the game. Additional insight into how the NRUBC programme is received by players, teammates and their families, needs investigation. Competing interests S.J Sullivan, A Gray and P Handcock: None. K Collins was involved in the development of the Northland Blue Card Programme but was not involved in the data analysis. None.

The Beneficial Effect of Parasympathetic Reactivation on Sympathetic Drive During Simulated Rugby Sevens

PURPOSE To determine whether a facilitated recovery via cold-water immersion (CWI) after simulated rugby sevens would influence parasympathetic reactivation and repeated-sprint (RS) performance across 6 matches in a 2-d tournament. METHODS Ten male team-sport athletes completed 6 rugby sevens match simulations over 2 d with either postmatch passive recovery (PAS) or CWI in a randomized crossover design. Parasympathetic reactivation was determined via the natural logarithm of the square root of the mean of the sum of the squares of differences between adjacent R-R intervals (ln rMSSD). RS performance was calculated as time taken (s) to complete 6 × 30-m sprints within the first half of each match. RESULTS There were large increases in postintervention ln rMSSD between CWI and PAS after all matches (ES 90% CL: +1.13; ±0.21). Average heart rate (HR) during the RS performance task (HRAverage RS) was impaired from baseline from match 3 onward for both conditions. However, HRAverage RS was higher with CWI than with PAS (ES 90% CL: 0.58; ±0.58). Peak HR during the RS performance task (HRPeak RS) was similarly impaired from baseline for match 3 onward during PAS and for match 4 onward with CWI. HRPeak RS was very likely higher with CWI than with PAS (ES 90% CL: +0.80; ±0.56). No effects of match or condition were observed for RS performance, although there were moderate correlations between the changes in HRAverage RS (r 90% CL: -0.33; ±0.14), HRPeak RS (r 90% CL: -0.38; ±0.13), and RS performance. CONCLUSION CWI facilitated cardiac parasympathetic reactivation after a simulated rugby sevens match. The decline in average and peak HR across matches was partially attenuated by CWI. This decline was moderately correlated with a reduction in RS performance.

Reliability of repeated isometric neck strength and endurance testing in a simulated contact posture.

Abstract Salmon, DM, Handcock, PJ, Sullivan, SJ, Rehrer, NJ, and Niven, BE. Reliability of repeated isometric neck strength and endurance testing in a simulated contact posture. J Strength Cond Res 29(3): 637–646, 2015—The purpose of this study was to examine the reliability of repeated isometric measurements of neck strength and endurance in a simulated rugby contact posture. Data were collected from healthy active university students (n = 20) over 3 sessions. Each session consisted of a single maximal voluntary contraction (MVC) and endurance trial for extension and flexion. The endurance trials were analyzed to determine the area under the force curve (%AUC) and the time to fatigue (TTF). Reliability was calculated using the SEM and minimal detectable change (MDC). The results revealed that the MVC values for extension were nonsignificant for session (p = 0.21), whereas some session differences were seen for flexion (p = 0.01), where session 1, 115.3 N was less than session 3, 126.4 N (p = 0.03). For %AUC, flexion values (%AUC 86.0) were greater than extension (%AUC 59.4) (p = 0.02). A similar effect was observed for TTF with flexion (125.0 seconds) having significantly greater TTF than extension (86.1 seconds). For peak force, the greatest SEM and MDC were achieved for extension (15.3 and 42.3 N), while flexion produced lower values (11.3 and 31.2 N). In contrast, for the endurance trials, SEM and MDC were greater in flexion than in extension. The findings from this study indicate that the neck musculature can be reliably assessed in a simulated contact posture. For peak force, extension provided more consistent measures across time as there seems to be a learning effect for flexion. Additionally, the SEM and MDC scores provide a useful tool for future assessment of neck strength and endurance.