Thierry Bernard

Time-of-day effects in maximal anaerobic leg exercise

Abstract Time of day variations in maximal anaerobic leg exercise were studied in 23 men mean age 23 (SD 3) years. All the subjects performed two anaerobic tests (force-velocity and multi-jump tests) and those familiar with sprinting ran an additional 50-m dash (n=16). The maximal anaerobic powers for cycling and jumping (Pcycling and Pjump) and maximal anaerobic velocity (peak) were performed consecutively in the same order for all tests. The force-velocity and force-power relationships were established to determine Pcycling. The flight time (tf) and the ground contact time (tc) were recorded from five consecutive jumps on a jump-ergometer to calculate Pjump. The peak was measured between the 35th and the 45th m during the dash-run. The test schedules were at 0900, 1400 and 1800 hours on separate days in random order. Rectal temperatures (Tre) and body mass (mb) were measured before each test. The Tre increased significantly from 0900 to 1800 hours (P<0.001) but mb did not vary during the day (P>0.05). The Pcycling and Pjump were higher at 1400 and 1800 hours than at 0900 hours. The differences between the morning and the afternoon reached 3% (P<0.05) for Pcycling and 5%–7% for Pjump (P<0.01). The time-of-day effect was significant for tf (P<0.05) but not for tc. During the dash-run tests, the differences almost reached significance for peak between 0900 and 1800 hours (P=0.0544). No significant variations were observed between 1400 and 1800 hours for cycling, jumping and running tests. A time-of-day effect in the maximal anaerobic power of cycle and multi-jump tests existed. Such variations would have pronounced effects when expressed in competitions.

Age-related Changes in Triathlon Performances

The aim of this study was two-fold: i) to analyse age-related declines in swimming, cycling, and running performances for Olympic and Ironman triathlons, and ii) to compare age-related changes in these three disciplines between the Olympic and Ironman triathlons. Swimming, cycling, running and total time performances of the top 10 males between 20 and 70 years of age (in 5 years intervals) were analysed for two consecutive world championships (2006 and 2007) for Olympic and Ironman distances. There was a lesser age-related decline in cycling performance (p<0.01) compared with running and swimming after 55 years of age for Olympic distance and after 50 years of age for Ironman distance. With advancing age, the performance decline was less pronounced (p<0.01) for Olympic than for Ironman triathlon in cycling (>55 years) and running (>50 years), respectively. In contrast, an age-related decline in swimming performance seemed independent of triathlon distance. The age-related decline in triathlon performance is specific to the discipline, with cycling showing less declines in performance with age than swimming and running. The magnitude of the declines in cycling and running performance at Ironman distance is greater than at Olympic distance, suggesting that task duration exerts an important influence on the magnitude of the age-associated changes in triathlon performance.

Influence of cycling cadence on subsequent running performance in triathletes.

PURPOSE The purpose of this study was to investigate the influence of different cycling cadences on metabolic and kinematic parameters during subsequent running. METHODS Eight triathletes performed two incremental tests (running and cycling) to determine maximal oxygen uptake (VO2max) and ventilatory threshold (VT) values, a cycling test to assess the energetically optimal cadence (EOC), three cycle-run succession sessions (C-R, 30-min cycle + 15-min run), and one 45-min isolated run (IR). EOC, C-R, and IR sessions were realized at an intensity corresponding to VT + 5%. During the cycling bouts of C-R sessions, subjects had to maintain one of the three pedaling cadences corresponding to the EOC (72.5 +/- 4.6 rpm), the freely chosen cadence (FCC; 81.2 +/- 7.2 rpm), and the theoretical mechanical optimal cadence (MOC, 90 rpm; Neptune and Hull, 1999). RESULTS Oxygen uptake (VO2) increased during the 30-min cycling only at MOC (+12.0%) and FCC (+10.4%). During the running periods of C-R sessions, VO2, minute ventilation, and stride-rate values were significantly higher than during the IR session (respectively, +11.7%, +15.7%, and +7.2%). Furthermore, a significant effect of cycling cadence was found on VO2 variability during the 15-min subsequent run only for MOC (+4.1%) and FCC (+3.6%). CONCLUSION The highest cycling cadences (MOC, FCC) contribute to an increase in energy cost during cycling and the appearance of a VO2 slow component during subsequent running, whereas cycling at EOC leads to a stability in energy cost of locomotion with exercise duration. Several hypotheses are proposed to explain these results such as changes in fiber recruitment or hemodynamic modifications during prolonged exercise.

Age-Related Decline in Olympic Triathlon Performance: Effect of Locomotion Mode

This study describes the decline in performance with age during Olympic triathlon Age Groups World Championships among the different locomotion modes. Mean performance of top 10 performers were analyzed for each group of age using the exponential model proposed by Baker, Tang, and Turner (2003, Experimental Aging Research, 29, 47–65). Comparison in performance decline was done between locomotion modes. Decline in performance in triathlon as a function of age follows an exponential model. A significant interaction effect between age and locomotion mode was observed on performance values. In swimming, a significant decrease was observed close to 5% per year after 45 years. Decline in performance was less pronounced in cycling until 60 years. Analysis of the effect of age in the different locomotion modes of a triathlon could provide information for maintaining quality of life with aging.

Effect of cycling cadence on subsequent 3 km running performance in well trained triathletes

Objectives: To investigate the effect of three cycling cadences on a subsequent 3000 m track running performance in well trained triathletes. Methods: Nine triathletes completed a maximal cycling test, three cycle-run succession sessions (20 minutes of cycling + a 3000 m run) in random order, and one isolated run (3000 m). During the cycling bout of the cycle-run sessions, subjects had to maintain for 20 minutes one of the three cycling cadences corresponding to 60, 80, and 100 rpm. The metabolic intensity during these cycling bouts corresponded approximately to the cycling competition intensity of our subjects during a sprint triathlon (> 80% V̇o2max). Results: A significant effect of the prior cycling exercise was found on middle distance running performance without any cadence effect (625.7 (40.1), 630.0 (44.8), 637.7 (57.9), and 583.0 (28.3) seconds for the 60 rpm run, 80 rpm run, 100 rpm run, and isolated run respectively). However, during the first 500 m of the run, stride rate and running velocity were significantly higher after cycling at 80 or 100 rpm than at 60 rpm (p<0.05). Furthermore, the choice of 60 rpm was associated with a higher fraction of V̇o2max sustained during running compared with the other conditions (p<0.05). Conclusions: The results confirm the alteration in running performance completed after the cycling event compared with the isolated run. However, no significant effect of the cadence was observed within the range usually used by triathletes.

Influence of the menstrual cycle phase and menstrual symptoms on maximal anaerobic performance

PURPOSE This study was designed to analyze the effect of the menstrual cycle phase on maximal anaerobic performance during short-term anaerobic tests. METHODS Seven eumenorrheic women (NOC) and 10 women using monophasic oral contraceptives (OC) performed three anaerobic tests (force-velocity, multi-jump, and squatting jump tests) during menstruation (M: between days 1 and 4), the midfollicular phase (F: between days 7 and 9), and the midluteal phase (L: between days 19 and 21) of the ovarian cycle. Follicular and luteal phases were confirmed by serum progesterone levels. The order of testing sessions was randomly assigned and a 15-min standardized warm-up preceded each testing session. Rectal temperatures were taken before (Trec(b)) and after (Trec(a)) warm-up. RESULTS No significant differences were observed among M, F, and L in Trec(b), Trec(a) maximal cycling power (Pmax(c)), maximal jumping power (Pmax(j)), or maximal height of jump (h(j)) in either NOC or OC. Ten of the women suffered premenstrual or menstrual symptoms (MS); the other seven did not report any premenstrual or menstrual discomfort (NMS). Presence or absence of symptoms was not correlated with oral contraceptive use. No significant differences were observed among the three stages of the menstrual cycle in Pmax(c), Pmax(j), or h(j) in NMS. In MS, only Pmax(j) decreased by 8% in M compared with that in F (P < 0.05). CONCLUSIONS Although there were no significant differences in maximal anaerobic performance during different menstrual cycle phases, results of this study suggest that the presence or absence of premenstrual or menstrual syndrome symptoms may have an effect, possibly through an action on the stretch-shortening cycle of tendons and ligaments.

Evaluation of habitual physical activity from a week's heart rate monitoring in French school children

Habitual physical activity (HPA) was studied in 30 boys and 34 girls aged 6–11 years. All the children performed a shuttle run test (SRT) to assess maximal heart frequency (fcmaxSRT) and to evaluate maximal oxygen uptake (VO2maxSRT). Heart rate (fc) was measured continuously from Monday to Sunday, using a heart rate counter. The time spent at fc greater than 140 beats · min−1 (tfc>140) and at fc greater than 160 beats · min−1 (tfc>160) permitted HPA to be evaluated. The daily heart rate (fcd) and the percentage of heart rate reserve (%fcrd) were calculated to evaluate the metabolic activity. In the boys and girls, fcd and %fcrd varied little with age. The metabolic activity varied in a rhythmical way during the week and was higher during school days than during free days (P < 0.001). The children were more active during school days (ds) than during the free days (df). This observation was particularly marked in the boys having tfc>140 being twice as high during ds compared to df [tfc>140, ds 85 (SD 25), df 40 (SD 26) min; tfc>160, ds 36 (SD 19), df 16 (SD 13) min]. During dstfc>160was greater in the boys than in the girls (P < 0.01) . The same held for tfc>140and % fcrd from the age of 9 years (P < 0.001) . It was during the recreation periods that the differences between the boys and the girls were observed (P < 0.01). There was no significant difference between the boys and the girls during lessons, in the evening and during df (% fcrd 26–28%, tfc>14035–45 min, tfc>16010–18 min). In contrast, the children who were physically active in a sports club, had less spontaneous physical activity and %fcrd, tfc>140, tfc>160and VO2maxSRT were identical to those of the other children.

Continuous heart rate monitoring over 1 week in teenagers aged 11-16 years

Abstract Heart rate (HR) was monitored in 66 French pubertal boys (B, n=28) and girls (G, n=38) aged 11–16 years to evaluate habitual physical activity (HPA) over a 1-week period in the winter. The HR and the percentage of heart rate reserve (%HRR) were taken to be indexes of the metabolic activity for the whole day and for the different parts of the day. The HPA was evaluated from the time spent each day below 50%HRR, between 50%–70%HRR and above 70%HRR, which related to the time spent in no or low physical activity (NLPA), moderate physical activity (MPA) and vigorous physical activity (VPA), respectively. No sex differences were observed in the average %HRR each day {%HRRmean, [B 30 (SD 4)%; G 32 (SD 4)%]} or in NLPA [B 715 (SD 61) min, G 711 (SD 81) min] and VPA [B 19 (SD 16) min, G 21 (SD 21) min] throughout the week. During school days, daily %HRRmean was 7% smaller in 14–16 year olds compared to 11–13 year olds. This was linked to a decrease in MPA and a concomitant increase in NLPA (P<0.05). Daily %HRRmean varied significantly during the week (range: 28–34% HRR). There were significant differences among the periods of the day (P<0.05). The HR was the greatest during physical education lessons [128 (SD 11) beats · min−1], recreation [113 (SD 15) beats · min−1] and lunch break [108 (SD 12) beats · min−1] and the lowest during the evening [94 (SD 10) beats · min−1]. It was only during the lunch breaks that %HRRmean was greater (P<0.05) on school days than on free days. Of all the teenagers studied 32% were considered active during the week.

Distribution of power output during the cycling stage of a Triathlon World Cup.

PURPOSE The aim of this study was to evaluate the power output (PO) during the cycle phase of the Beijing World Cup test event of the Olympic triathlon in China 2008. METHODS Ten elite triathletes (5 females, 5 males) performed two laboratory tests: an incremental cycling test during which PO, HR at ventilatory thresholds (VT1 and VT2), and maximal aerobic power (MAP) were assessed, and a brief all-out test to determine maximal anaerobic power output (MAnP). During the cycle part of competition, PO and HR were measured directly with portable device. The amount of time spent below PO at VT1 (zone 1), between PO at VT1 and VT2 (zone 2), between PO at VT2 and MAP (zone 3) and above MAP (zone 4) was analyzed. RESULTS A significant decrease in PO, speed, and HR values was observed during the race. The distribution of time was 51 +/- 9% for zone 1, 17 +/- 6% for zone 2, 15 +/- 3% for zone 3, and 17 +/- 6% was performed at workloads higher than MAP (zone 4). From HR values, the triathletes spent 27 +/- 12% in zone 1, 26 +/- 8% in zone 2, and 48 +/- 14% above VT2. CONCLUSIONS This study indicates a progressive reduction in speed, PO, and HR, coupled with an increase in variability during the event. The Olympic distance triathlon requires a higher aerobic and anaerobic involvement than constant-workload cycling exercises classically analyzed in laboratory settings (i.e., time trial) or Ironman triathlons. Furthermore, monitoring direct PO could be more suitable to quantify the intensity of a race with pacing strategies than classic HR measurements.

Relationships between oxygen consumption and heart rate in transitory and steady states of exercise and during recovery: influence of type of exercise

Abstract  Relationships between percentage of maximal oxygen consumption () and percentage of maximal heart rate reserve () were compared during steady states of exercise (S), transitory states of exercise (T) and a 5-min recovery period (R). Male adults [mean age 27 (SD 10) years] were studied exercising on a treadmill (TR, ), cycle ergometer (CE, ) and arm traction bench (ATB, ). The exercise intensity was adjusted according to the subjects in order to reach exhaustion in 4–5 steps of 2 min (ATB) or 3 min (TR, CE). The 1st min of each stage was considered as T and the last minute of each stage as S. The oxygen consumption () and heart rate () were recorded simultaneously. Significant correlations were observed for each type of exercise and for each state between and ( range 0.87–1.00). During T and R, the versus relationships were laterally shifted, suggesting a resetting of control mechanisms. In S, the intercept was greater than in T and R; in T, the slope was greater than in S and R. The could be predicted from individual versus relationships during T and R as is usually done in S using specific equations. Taking into consideration the average relationships established on the three ergometers, the standard error of the predicted during S and T reached 10%–20% and 22%–38% in R. During exercise, the higher the intensity the better was the prediction of from ( range 0.46–0.60, ). Therefore except at high exercise intensities, it was found that individual relationships had to be used to obtain an accurate estimation of .