Didier Chollet

Effect of swimming velocity on arm coordination in the front crawl: a dynamic analysis

We examined the preferred mode of arm coordination in 14 elite male front-crawl swimmers. Each swimmer performed eight successive swim trials in which target velocity increased from the swimmers usual 3000-m velocity to his maximal velocity. Actual swim velocity, stroke rate, stroke length and the different arm stroke phases were then calculated from video analysis. Arm coordination was quantified by an index of coordination based on the lag time between the propulsive phases of each arm. The index expressed the three coordination modes in the front crawl: opposition, catch-up and superposition. First, in line with the dynamic approach to movement coordination, the index of coordination could be considered as an order parameter that qualitatively captured arm coordination. Second, two coordination modes were observed: a catch-up pattern (index of coordination = −8.43%) consisting of a lag time between the propulsive phases of each arm, and a relative opposition pattern (index of coordination = 0.89%) in which the propulsive phase of one arm ended when the propulsive phase of the other arm began. An abrupt change in the coordination pattern occurred at the critical velocity of 1.8 m · s−1, which corresponded to the 100-m pace: the swimmers switched from catch-up to relative opposition. This change in coordination resulted in a reorganization of the arm phases: the duration of the entry and catch phase decreased, while the duration of the pull and push phases increased in relation to the whole stroke. Third, these changes were coupled to increased stroke rate and decreased stroke length, indicating that stroke rate, stroke length, the stroke rate/stroke length ratio, as well as velocity, could be considered as control parameters. The control parameters can be manipulated to facilitate the emergence of specific coordination modes, which is highly relevant to training and learning. By adjusting the control and order parameters within the context of a specific race distance, both coach and swimmer will be able to detect the best adapted pattern for a given race pace and follow how arm coordination changes over the course of training.

Reliability of resting and postexercise heart rate measures.

In this study, we compared the reliability of short-term resting heart rate (HR) variability (HRV) and postexercise parasympathetic reactivation (i.e., HR recovery (HRR) and HRV) indices following either submaximal or supramaximal exercise. On 4 different occasions, beat-to-beat HR was recorded in 15 healthy males (21.5 ± 1.4 yr) during 5 min of seated rest, followed by submaximal (Sub) and supramaximal (Supra) exercise bouts; both exercise bouts were followed by 5 min of seated recovery. Reliability of all HR-derived indices was assessed by the typical error of measurement expressed as a coefficient of variation (CV,%). CV for HRV indices ranged from 4 to 17%, 7 to 27% and 41 to 82% for time domain, spectral and ratio indices, respectively. The CV for HRR ranged from 15 to 32%. Spectral CVs for HRV were lower at rest compared with Supra (e.g., natural logarithm of the high frequency range (LnHF); 12.6 vs. 26.2%; P=0.02). HRR reliability was not different between Sub and Supra (25 vs. 14%; P=0.10). The present study found discrepancy in the CVs of vagal-related heart rate indices; a finding that should be appreciated when assessing changes in these variables. Further, Supra exercise was shown to worsen the reliability of HRV-spectral indices.

The influence of prior cycling on biomechanical and cardiorespiratory response profiles during running in triathletes

Abstract The aim of the present study was to determine the effects of 40 km of cycling on the biomechanical and cardiorespiratory responses measured during the running segment of a classic triathlon, with particular emphasis on the time course of these responses. Seven male triathletes underwent four successive laboratory trials: (1) 40 km of cycling followed by a 10-km triathlon run (TR), (2) a 10-km control run (CR) at the same speed as TR, (3) an incremental treadmill test, and (4) an incremental cycle test. The following ventilatory data were collected every minute using an automated breath-by-breath system: pulmonary ventilation (V˙E, l · min−1), oxygen uptake (V˙O2, ml · min−1 · kg−1), carbon dioxide output (ml · min−1), respiratory equivalents for oxygen (V˙E/V˙O2) and carbon dioxide (V˙E/V˙CO2), respiratory exchange ratio (R) respiratory frequency (f, breaths · min−1), and tidal volume (ml). Heart rate (HR, beats · min−1) was monitored using a telemetric system. Biomechanical variables included stride length (SL) and stride frequency (SF) recorded on a video tape. The results showed that the following variables were significantly higher (analysis of variance, P < 0.05) for TR than for CR: V˙O2 [51.7 (3.4) vs 48.3 (3.9) ml · kg−1 · min−1, respectively], V˙E [100.4 (1.4) l · min−1 vs 84.4 (7.0) l · min−1], V˙E/V˙O2 [24.2 (2.6) vs 21.5 (2.7)] V˙E/V˙CO2 [25.2 (2.6) vs 22.4 (2.6)], f [55.8 (11.6) vs 49.0 (12.4) breaths · min−1] and HR [175 (7) vs 168 (9) beats · min−1]. Moreover, the time needed to reach steady-state was shorter for HR and V˙O2 (1 min and 2 min, respectively) and longer for V˙E (7 min). In contrast, the biomechanical parameters, i.e. SL and SF, remained unchanged throughout TR versus CR. We conclude that the first minutes of the run segment after cycling in an experimental triathlon were specific in terms of V˙O2 and cardiorespiratory variables, and nonspecific in terms of biomechanical variables.

Inter-limb coordination in swimming: Effect of speed and skill level

The aim of this study was to examine the effects of swimming speed and skill level on inter-limb coordination and its intra-cyclic variability. The elbow-knee continuous relative phase (CRP) was used as the order parameter to analyze upper-lower limbs coupling during a complete breaststroke cycle. Twelve recreational and 12 competitive female swimmers swam 25m at a slow speed and 25m at maximal speed. Underwater and aerial side views were mixed and genlocked with an underwater frontal view. The angle, angular velocity, and phase were calculated for the knee and elbow by digitizing body marks on the side view. Three cycles were analyzed, filtered, averaged, and normalized in percentage of the total cycle duration. The competitive swimmers showed greater intra-cyclic CRP variability, indicating a combination of intermediate phase and in-phase knee-elbow coupling within a cycle. This characteristic was more marked at slow speed because more time was spent in the glide period of the stroke cycle, with the body completely extended. Conversely, because they spent less time in the glide, the recreational swimmers showed lower intra-cyclic CRP variability (which is mostly in the in-phase coordination mode), resulting in superposition of contradictory actions (propulsion of one limb during the recovery of the other limb).

Performance and drag during drafting swimming in highly trained triathletes.

PURPOSE The influence of drafting was studied on the swimming performance, metabolic response, and passive drag of eight triathletes. METHODS The performance in drafting position was measured directly behind another swimmer during a 400-m swim and compared with the nondrafting position. Metabolic response concerned VO(2), blood lactate, stroke rate, stroke length, and rating of perceived exertion. Drag was measured by passive towing. RESULTS In drafting position, the triathletes swam on average faster (3.2%) over the 400-m swim than in nondrafting position (4 min, 47.69 +/- 10.35 s vs 4 min, 57.25 +/- 7.24 s; P < 0.01). Blood lactate and stroke rate were significantly lower (9.6 mM vs 10.8 mM; 39.9 cyclexmin(-1) vs 41.3 cyclexmin(-1) P < 0.02) and stroke length higher (2.10 mx cycle(-1) vs 1.97 mxcycle(-1), P < 0.01) than in nondrafting position. VO(2) and rating of perceived exertion were not statistically different. Passive drag was lower in drafting than in nondrafting position (P < 0.01). However, the gain in drag decreased with the towed velocity (from 26% at 1.1 mxs(-1) to 13% at 1.7mxs(-1)). In drafting position, the performance gain was related to the 400-m time (r = 0.80, P < 0.01) and to the skinfold thickness (r = 0.94, P < 0.01), with faster and leaner swimmers having greater gains of performance. CONCLUSIONS Swimming behind another swimmer in a race is advantageous for triathletes.

Arm coordination, power, and swim efficiency in national and regional front crawl swimmers

The effects of skill level on index of arm coordination (IdC), mechanical power output (P(d)), and swim efficiency were studied in front crawlers swimming at different speeds. Seven national and seven regional swimmers performed an arms-only intermittent graded speed test on the MAD-system and in a free condition. The MAD-system measured the drag (D) and P(d). Swimming speed (v), stroke rate (SR), stroke length (SL), stroke index (SI), relative entry, pull, push, and recovery phase durations, and IdC were calculated. Swim efficiency was assessed from SI, the coefficient of variation of calculated hip intra-cyclic velocity variations (IVV), and the efficiency of propulsion generation, i.e., the ratio of v(2) to tangential hand speed squared (u(2)). Both groups increased propulsive continuity (IdC) and hand speed (u) and applied greater P(d) to overcome active drag with speed increases (p<.05). This motor organization adaptation was adequate because SI, IVV, and v(2)/u(2) were unchanged. National swimmers appeared more efficient, with greater propulsive continuity (IdC) and P(d) to reach higher v than regional swimmers (p<.05). The regional swimmers exhibited a higher u and lower SI, IVV, and v(2)/u(2) compared to national swimmers (p<.05), which revealed lower effectiveness to generate propulsion, suggesting that technique is a major determinant of swimming performance.

Auditory concurrent feedback benefits on the circle performed in gymnastics.

Abstract In this study, we examined the effectiveness of auditory concurrent feedback on body segmental alignment during the circle movement performed on a pommel horse. Eighteen gymnasts were assigned to one of two groups: a concurrent auditory feedback group (experimental) or a control group that received no concurrent feedback. After 2 weeks of training (300 circles), the body segmental alignment (BSA) of the experimental group had improved by 2.3% between the pre test (85.7 ± 4.8% BSAmax) and the post test (87.7 ± 4.0% BSAmax). Furthermore, the results of a retention test administered 2 weeks after the post test revealed no decline in performance for the experimental group. No gains in body segmental alignment were found for the control group. It was concluded that augmented auditory feedback made available in real time can be used to correct complex movements, such as the circle movement on a pommel horse, and does not appear to lead to information-dependence despite the frequent administration of feedback. The auditory signal available in real time could help gymnasts to become more objective about their own intrinsic information necessary for the refinement of the circle movement.

Ventilatory responses during experimental cycle-run transition in triathletes.

PURPOSE AND METHODS To determine the effects of cycling on a subsequent triathlon run, nine male triathletes underwent four successive laboratory trials: 1) an incremental treadmill test, 2) an incremental cycle test, 3) 30 min of cycling followed by 5 km of running (C-R), and 4) 30 min of running followed by 5 km of running (R-R). Before and 10 min after the third and fourth trials, the triathletes underwent pulmonary function testing including spirometry and diffusing capacity testing for carbon monoxide (DL(CO)). During the C-R and R-R trials, arterialized blood samples were obtained to measure arterial oxygen pressure (PaO2). During all trials, ventilatory data were collected every minute using an automated breath-by-breath system. RESULTS The results showed that 1) the oxygen uptake (VO2) observed during subsequent running was similar for the C-R and R-R trials; 2) the ventilatory response (VE) during the first 8 min of subsequent running was significantly greater in the C-R than in R-R trial (P < 0.05); 3) only the C-R trial induced a significant increase (P < 0.05) in residual volume (RV), functional residual capacity (FRC), and the ratio of residual volume to total lung capacity (RV/TLC); and 4) although a significant decrease (P < 0.05) in DL(CO) was noted after C-R, no difference between the two exercise trials was found for the maximal drop in PaO2. CONCLUSIONS We concluded that 1) the C-R trial induced specific alterations in pulmonary function that may be associated with respiratory muscle fatigue and/or exercise-induced hypoxemia, and 2) the greater VE observed during the first minute of running after cycling was due to the specificity of cycling. This reinforces the necessity for triathletes to practice multi-trial training to stimulate the physiological responses experienced during the swim-cycle and the cycle-run transitions.

Effect of cold or thermoneutral water immersion on post-exercise heart rate recovery and heart rate variability indices

This study aimed to investigate the effect of cold and thermoneutral water immersion on post-exercise parasympathetic reactivation, inferred from heart rate (HR) recovery (HRR) and HR variability (HRV) indices. Twelve men performed, on three separate occasions, an intermittent exercise bout (all-out 30-s Wingate test, 5 min seated recovery, followed by 5 min of submaximal running exercise), randomly followed by 5 min of passive (seated) recovery under either cold (CWI), thermoneutral water immersion (TWI) or control (CON) conditions. HRR indices (e.g., heart beats recovered in the first minute after exercise cessation, HRR(60)(s)) and vagal-related HRV indices (i.e., natural logarithm of the square root of the mean of the sum of the squares of differences between adjacent normal R-R intervals (Ln rMSSD)) were calculated for the three recovery conditions. HRR(60)(s) was faster in water immersion compared with CON conditions [30+/-9 beats min(-)(1) for CON vs. 43+/- 10 beats min(-)(1) for TWI (P=0.003) and 40+/-13 beats min(-)(1) for CWI (P=0.017)], while no difference was found between CWI and TWI (P=0.763). Ln rMSSD was higher in CWI (2.32+/-0.67 ms) compared with CON (1.98+/-0.74 ms, P=0.05) and TWI (2.01+/-0.61 ms, P=0.08; aES=1.07) conditions, with no difference between CON and TWI (P=0.964). Water immersion is a simple and efficient means of immediately triggering post-exercise parasympathetic activity, with colder immersion temperatures likely to be more effective at increasing parasympathetic activity.

Effect of breathing pattern on arm coordination symmetry in front crawl.

Seifert, L, Chehensse, A, Tourny-Chollet, C, Lemaitre, F, Chollet, D. Effect of breathing pattern on arm coordination symmetry in front crawl. J Strength Cond Res 22(5): 1670-1676, 2008-This study analyzed the relationship between breathing pattern and arm coordination symmetry in 11 expert male swimmers who performed the front crawl at their 100-m race pace using seven randomized breathing patterns. Two indexes of coordination (IdCP and IdCNP) and a symmetry index (SI) based on the difference of IdCP − IdCNP were calculated. IdCP calculated the lag time between the beginning of arm propulsion on the nonpreferential breathing side and the end of arm propulsion on the preferential breathing side; IdCNP did the converse. The IdCP and IdCNP comparisons and the SI showed coordination asymmetries among the seven breathing patterns. Specifically, breathing to the preferential side led to an asymmetry, in contrast to the other breathing patterns, and the asymmetry was even greater when the swimmer breathed to his nonpreferential side. These findings highlight the effect of breathing laterality in that coordination was symmetric in patterns with breathing that was bilateral, axed (as in breathing with a frontal snorkel), or removed (as in apnea). One practical application is that arm coordination asymmetry can be prevented or reduced by using breathing patterns that balance the coordination.