Patrick Pelayo

Characterising the slope of the distance–time relationship in swimming

The aim of the present study was to assess whether the critical speed calculated by the slope of the distance-time relationship (S(d-t)) represents the boundary between the heavy and severe intensity domains in swimming and would be sustainable during intermittent exercise. Nine competitive male swimmers (mean+/-SD: aged 21.2+/-2.6 yrs; peak (.)VO2 of 3866+/-529 mL min(-1)) performed, (a) four fixed-distance (100-200-400-800 m) all-out efforts to determine S(d-t) and peak (.)VO2; (b) three constant-speed efforts to exhaustion (TTE) at and 5% above and below S(d-t) (S(d-t)(+5%) and S(d-t)(-5%), respectively); (c) a set of 10 x 400 m at S(d-t) with 40-s recovery in between. Capillary blood lactate concentration ([La](B)), oxygen uptake ((.)VO2), and RPE remained stable at S(d-t)(-5%) (TTE=48.9+/-14.1 min) with end values of 3.8+/-1.9 mmol L(-1), 87+/-14% peak (.)VO2, and 4.7+/-1.3. TTE decreased at S(d-t)(+5%) (8.6+/-3.1 min), with end [La](B) of 10.2+/-1.9 mmol L(-1). Peak (.)VO2 was reached at exhaustion. Similarly, S(d-t) could only be maintained for 24.3+/-7.7 min with an increase in RPE and [La](B), (.)VO2 reaching its peak (95+/-5% peak VO2). RPE increased but [La](B) remained stable throughout the ten 400 m blocks performed at S(d-t) (overall time of 53.9+/-2.7 min). The physiological responses when swimming 5% below and 5% above S(d-t) are those characterising the heavy and severe intensity domain, respectively. While S(d-t) lies within the severe intensity domain, intermittent swims at this intensity induce [La](B) steady state alongside high rates of perceived exertion.

Changes in swimming technique during time to exhaustion at freely chosen and controlled stroke rates

Abstract The aim of this study was to assess technical changes during constrained swimming in time-to-exhaustion tests. Ten swimmers of national standard performed a maximal 400-m front crawl and two sets of exhaustion tests at 95%, 100%, and 110% of mean 400-m speed. In the first set (free), swimmers had to maintain their speeds until exhaustion and mean stroke rate was recorded for each test. In the second set (controlled), the same speed and individual corresponding stroke rate were imposed. The durations of the exhaustion tests, relative durations of the stroke phases, and arm coordination were analysed. For each speed in the “controlled” set, the exhaustion tests were shorter. Moreover, variables were consistent, suggesting a stabilization of stroke technique. Under the free condition, stroke rate increased to compensate for the decrease in stroke length. At the same time, swimmers reduced the relative duration of their non-propulsive phases in favour of the propulsive phases. Thus, swimmers changed their arm coordination, which came close to an opposition mode. These two constraints enable swimmers both to maintain their stroking characteristics and develop compensatory mechanisms to maintain speed. Moreover, stroke rate can be seen as a useful tool for controlling arm technique during paced exercise.

On the quantitative relationships between individual/occupational risk factors and low back pain prevalence using nonparametric approaches.

OBJECTIVESnTo explore dual quantitative relationships between low back pain (LBP) prevalence and different individual and occupational risk factors, and detect the most important ones which can be used as weighted input data in LBP prediction diagnosis models, providing effective tools to help with the implementation of protection and prevention strategies among hospital staff.nnnMETHODSnFourteen predictor individual risk factors (e.g., age, gender, body mass index BMI [kg/m(2)], domestic activity, etc.) and 17 occupational risk factors (e.g., job status, standing hours/day, sufficient break time, job dissatisfaction, etc.) were collected using self-reported questionnaire among the staff of Sacré-Coeur hospital - Lebanon (used as a case study), and correlated with LBP prevalence using Kendalls tau-b bivariate nonparametric approaches.nnnRESULTSnThis study indicates that among the investigated occupational risk factors, job status, working hours/day, and standing hours/day are the most influencing on LBP prevalence (highly correlated with other factors at 1 and 5% confidence levels). It also shows that strong positive (between 0.25 and 0.65)/negative (from -0.38 to -0.26) statistical correlations to LBP prevalence exist between these risk occupational factors and working days/week, sitting hours/day, job stress, job dissatisfaction, children care, and car driving. The weekly hours of domestic activity, the staff height, and gender type have proven also to be the strongest individual factors in aggravating LBP disease. These individual factors are highly correlated at 1% significance level (ranging between 0.28 and 0.49 for positive correlations, and from -0.49 to -0.25 for negative ones) to children care, weight, extra professional activity, and use of handling techniques.nnnCONCLUSIONSnThese obtained bivariate correlations can be used successfully by expert physicians in their decision making for LBP diagnosis.

Restauration fonctionnelle du rachis : effet du niveau initial de douleur sur les performances des sujets lombalgiques chroniques

Intensive care programs are very useful for the treatment of chronic low back pain; however, the initial pain intensity reported by patients may affect the degree of improvement following participation in such programs. The authors of this article aimed to determine whether an intensive spine functional restoration program would be as effective for individuals presenting with severe pain as those presenting with mild to moderate pain.

Moderator Effect of Burnout in Secondary School Context

Burnout is defined as a psychological syndrome with a three-dimensional construct: emotional/physical exhaustion, reduced sense of accomplishment and devaluation (e.g., Raedeke, Journal of Sport and Exercise Psychology, 19, 396–417, 1997). It may have very negative effects on subjects’ well-being. It has been studied in several domains, but we have found only one published study focused on pupils (Oger, Martin-Krumm, & Sarrazin, 2009) and none specifically in the domain of physical education (PE) at school. A perceived ability/performance model based on obtained marks during PE classes has been improved. In this model, burnout was presumed to interact with perceived ability to predict the results the students obtained. Results among 143 students revealed that a high burnout level inhibits the positive effect of a good perceived ability on performances. Burnout did not change anything for the students who have a low perceived ability. Burnout could be taken into account in the organization of the school year for the pupils’ well-being. Ongoing researches should test this hypothesis and study how variables such as optimism or motivation could be implicated in these processes.