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Matt B. Brearley and James P. Finn

Background:

Despite the thermal challenge of demanding workloads performed in high cabin temperatures while wearing heavy heat-retardant clothing, information on physiological responses to racing V8 Supercars in hot conditions is not readily available.

Purpose:

To describe the thermal, cardiovascular, and perceptual strain on V8 Supercar drivers competing in hot conditions.

Methods:

Thermal strain was indicated by body-core temperature using an ingested thermosensitive pill. Cardiovascular strain was assessed from heart rate, hydration status, and sweat rate. Perceptual strain was estimated from self-rated thermal sensation, thermal discomfort (modified Gagge scales), perceived exertion (Borg scale), and perceptual strain index.

Results:

Prerace body-core temperatures were (mean ± SD) 37.7°C ± 0.4°C (range 37.0°C to 38.2°C), rising to 39.0°C ± 0.4°C (range 38.4°C to 39.7°C) postrace. Driver heart rates were >160 and >170 beats/min for 85.3% and 46.7% of racing, respectively. Sweat rates were 1.06 ± 0.12 L/h or 13.4 ± 1.2 mL · kg−1 · h−1, and postrace dehydration was 0.6% ± 0.6% of prerace body mass. Drivers rated thermal sensation as hot (10.3 ± 0.9), thermal discomfort as uncomfortable (3.1 ± 1.0), and perceived exertion as very hard to very, very hard (8.7 ± 1.7) after the races. Overall physiological and perceptual strain were 7.4 ± 1.0 and 7.1 ± 1.2, respectively.

Conclusions:

Despite the use of cooling, V8 Supercar drivers endure thermal, cardiovascular, and perceptual strain during brief driving bouts in hot conditions.

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Thomas Zochowski, Elizabeth Johnson and Gordon G. Sleivert

Context:

Warm-up before athletic competition might enhance performance by affecting various physiological parameters. There are few quantitative data available on physiological responses to the warm-up, and the data that have been reported are inconclusive. Similarly, it has been suggested that varying the recovery period after a standardized warm-up might affect subsequent performance.

Purpose:

To determine the effects of varying post-warm-up recovery time on a subsequent 200-m swimming time trial.

Methods:

Ten national-caliber swimmers (5 male, 5 female) each swam a 1500-m warm-up and performed a 200-m time trial of their specialty stroke after either 10 or 45 min of passive recovery. Subjects completed 1 time trial in each condition separated by 1 wk in a counterbalanced order. Blood lactate and heart rate were measured immediately after warm-up and 3 min before, immediately after, and 3 min after the time trial. Rating of perceived exertion was measured immediately after the warm-up and time trial.

Results:

Time-trial performance was significantly improved after 10 min as opposed to 45 min recovery (136.80 ± 20.38 s vs 138.69 ± 20.32 s, P < .05). There were no significant differences between conditions for heart rate and blood lactate after the warm-up. Pre-time-trial heart rate, however, was higher in the 10-min than in the 45-min rest condition (109 ± 14 beats/min vs 94 ± 21 beats/min, P < .05).

Conclusions:

A post-warm-up recovery time of 10 min rather than 45 min is more beneficial to 200-m swimming time-trial performance.

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Thomas I. Gee, Duncan N. French, Karl C. Gibbon and Kevin G. Thompson

Purpose:

This study investigated the pacing strategy adopted and the consistency of performance and related physiological parameters across three 2000-m rowing-ergometer tests.

Methods:

Fourteen male well-trained rowers took part in the study. Each participant performed three 2000-m rowing-ergometer tests interspersed by 3–7 d. Throughout the trials, respiratory exchange and heart rate were recorded and power output and stroke rate were analyzed over each 500 m of the test. At the completion of the trial, assessments of blood lactate and rating of perceived exertion were measured.

Results:

Ergometer performance was unchanged across the 3 trials; however, pacing strategy changed from trial 1, which featured a higher starting power output and more progressive decrease in power, to trials 2 and 3, which were characterized by a more conservative start and an end spurt with increased power output during the final 500 m. Mean typical error (TE; %) across the three 2000-m trials was 2.4%, and variability was low to moderate for all assessed physiological variables (TE range = 1.4−5.1%) with the exception of peak lactate (TE = 11.5%).

Conclusions:

Performance and physiological responses during 2000-m rowing ergometry were found to be consistent over 3 trials. The variations observed in pacing strategy between trial 1 and trials 2 and 3 suggest that a habituation trial is required before an intervention study and that participants move from a positive to a reverse-J-shaped strategy, which may partly explain conflicting reports in the pacing strategy exhibited during 2000-m rowing-ergometer trials.

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Maria Konstantaki, Edward Winter and Ian Swaine

Context:

Forward propulsion in freestyle swimming is predominantly achieved through arm action. Few studies have assessed the effects of arm training on arm power and swimming performance, yet there have not been any investigations on the effects of arms-only swimming training on swimming performance and physiological responses to arm exercise.

Purpose:

To investigate the changes in arms-only and full-stroke swimming performance, movement economy and aerobic power after an arms-only swimming training program.

Methods:

Fifteen male county level swimmers were assigned either to an experimental (ES, n = 8) or control group (CS, n = 7). For six weeks ES performed arms-only freestyle swimming exercises for 20% of their weekly training distance three times per week, whereas CS performed their usual swimming training. Before and after the training program, both groups performed a) two time trials, 186 m using arms-only (186ARMS) and 372 m using full-stroke (372FULL) freestyle swimming, and b) an incremental arm-pulling exercise test. The time to complete the trials was recorded. Peak oxygen uptake (VO2peak), peak exercise intensity (EIpeak) submaximal oxygen uptake at 60 W (VO2−60) and exercise intensity at ventilatory threshold (VTW) were determined from the exercise test.

Results:

After training, ES had improved in 186ARMS (−14.2 ± 3.6%, P = .03), VO2−60 (−22.5 ± 2.3%, P = .04), EIpeak (+17.8 ± 4.2%, P = .03), and VTW (+18.9 ± 2.3%, P = .02), but not in VO2peak (P = .09) or in 372FULL (P = .07). None of the measures changed in CS (P > .05).

Conclusion:

Arms-only swimming training at 20% of the weekly training distance is an effective method to improve arm conditioning during the preparatory phase of the annual training cycle.

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Rob Duffield, Monique King and Melissa Skein

Purpose:

This study investigated the effects of hot conditions on the acute recovery of voluntary and evoked muscle performance and physiological responses following intermittent exercise.

Methods:

Seven youth male and six female team-sport athletes performed two sessions separated by 7 d, involving a 30-min exercise protocol and 60-min passive recovery in either 22°C or 33°C and 40% relative humidity. The exercise protocol involved a 20-s maximal sprint every 5 min, separated by constant-intensity exercise at 100 W on a cycle ergometer. Maximal voluntary contraction (MVC) and a resting evoked twitch (Pf) of the right knee extensors were assessed before and immediately following exercise and again 15, 30, and 60 min post exercise, and capillary blood was obtained at the same time points to measure lactate, pH, and HCO3. During and following exercise, core temperature, heart rate and rating of perceived exertion (RPE) were also measured.

Results:

No differences (P = 0.73 to 0.95) in peak power during repeated sprints were present between conditions. Post exercise MVC was reduced (P < .05) in both conditions and a moderate effect size (d = 0.60) indicated a slower percentage MVC recovered by 60 min in the heat (83 ± 10 vs 74 ± 11% recovered). Both heart rate and core temperature were significantly higher (P < .05) during recovery in the heat. Capillary blood values did not differ between conditions at any time point, whereas sessional RPE was higher 60 min post exercise in the heat.

Conclusions:

The current data suggests that passive recovery in warm temperatures not only delays cardiovascular and thermal recovery, but may also slow the recovery of MVC and RPE.

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Hervé Assadi and Romuald Lepers

Purposes:

To compare the physiological responses and maximal aerobic running velocity (MAV) during an incremental intermittent (45-s run/15-s rest) field test (45-15FIT) vs an incremental continuous treadmill test (TR) and to demonstrate that the MAV obtained during 45-15FIT (MAV45-15) was relevant to elicit a high percentage of maximal oxygen uptake (VO2max) during a 30-s/30-s intermittent training session.

Methods:

Oxygen uptake (VO2), heart rate (HR), and lactate concentration ([La]) were measured in 20 subjects during 2 maximal incremental tests and four 15-min intermittent tests. The time spent above 90% and 95% VO2max (t90% and t95% VO2max, respectively) was determined.

Results:

Maximal physiological parameters were similar during the 45-15FIT and TR tests (VO2max 58.6 ± 5.9 mL · kg−1 · min−1 for TR vs 58.5 ± 7.0 mL · kg−1 · min−1 for 45-15FIT; HRmax 200 ± 8 beats/min for TR vs 201 ± 7 beats/min for 45-15FIT). MAV45-15 was significantly (P < .001) greater than MAVTR (17.7 ± 1.1 vs 15.6 ± 1.4 km/h). t90% and t95% VO2max during the 30-s/30-s performed at MAVTR were significantly (P < .01) lower than during the 30-s/30-s performed at MAV45-15. Similar VO2 during intermittent tests performed at MAV45-15 and at MAVTR can be obtained by reducing the recovery time or using active recovery.

Conclusions:

The results suggested that the 45-15FIT is an accurate field test to determine VO2max and that MAV45-15 can be used during high-intensity intermittent training such as 30-s runs interspersed with 30-s rests (30-s/30-s) to elicit a high percentage of VO2max.

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Thomas W. Buford, Douglas B. Smith, Matthew S. O’Brien, Aric J. Warren and Stephen J. Rossi

Purpose:

The purpose of the present investigation was to examine the physiological response of collegiate wrestlers to their competitive season.

Methods:

Eleven Division I collegiate wrestlers (mean ± SD; 19.45 ± 1.13 y) volunteered and completed 4 testing sessions throughout the course of the collegiate wrestling season. Testing sessions were conducted pre-, mid-, and postseason, as well as before the national tournament. Testing consisted of weigh-in, skinfold body composition testing, and a 50-rep concentric, isokinetic leg extension muscle endurance test (180°/s). Muscular performance variables measured included peak torque, peak torque at fatigue, percent decline, and peak torque/body mass ratio.

Results:

A significant increase (P < .05) of 2.9% was observed for body mass between midseason and postseason (2.38 kg). From pre- to postseason, a mean increase of 3.8% (3.1 kg) was observed for body mass. An increase (P < .05) in BF% of 2.9% was observed between prenationals and postseason. No significant differences (P > .05) were observed between consecutive time points for quadriceps peak torque; however, there was a significant increase (P < .05) between preseason and prenationals (23.39 N·m). Peak torque at fatigue was greater (P < .05) at midseason than preseason, representing an increase of 9.82 N·m. Between midseason and prenationals testing, we observed an 11% increase (P < .05) in %DCLN. Finally, we noted an increase (P < .05) from 0.6 to 0.69 in peak torque/body mass ratio between preseason and prenationals.

Conclusions:

Our results indicate that while force values seem to suffer at midseason, the wrestlers compensated and were strongest just before their national competition.

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Kerry McGawley and Hans-Christer Holmberg

Purpose:

Cross-country-ski races place complex demands on athletes, with events lasting between approximately 3 min and 2 h. The aim of the current study was to compare the aerobic and anaerobic measures derived from a short time trial (TT) between male and female skiers using diagonal cross-country skiing.

Methods:

Twenty-four highly trained cross-country skiers (12 male and 12 female, age 17.4 ± 1.4 y, body mass 68.2 ± 8.9 kg, height 174 ± 8 cm) participated. The submaximal VO2–speed relationship and VO2max were derived from an incremental ramp test to exhaustion (RAMP), while the accumulated oxygen deficit (AOD), peak VO2, and performance time were measured during a 600-m TT.

Results:

The female skiers took longer to complete the TT than the males (209 ± 9 s vs 166 ± 7 s, P < .001) and exhibited a lower relative anaerobic contribution (20% ± 4% vs 24% ± 3%, P = .015) and a higher fractional utilization of VO2max (84% ± 4% vs 79% ± 5%, P = .007) than males. Although there was no significant difference in AOD between the sexes (40.9 ± 9.5 and 47.3 ± 7.4 mL/kg for females and males, respectively; P = .079), the mean difference ± 90% confidence intervals of 6.4 ± 6.0 mL/kg reflected a likely practical difference (ES = 0.72). The peak VO2 during the TT was significantly higher than VO2max during the RAMP for all participants combined (62.3 ± 6.8 vs 60.5 ± 7.2 mL · kg−1 · min−1, P = .011), and the mean difference ± 90% confidence intervals of 1.8 ± 1.1 mL · kg−1 · min−1 reflected a possible practical difference (ES = 0.25).

Conclusions:

These results show that performance and physiological responses to a self-paced TT lasting approximately 3 min differ between sexes. In addition, a TT may provide a valid measure of VO2max.

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Paola Zamparo, Ivan Zadro, Stefano Lazzer, Marco Beato and Luigino Sepulcri

Shuttle runs can be used to study the physiological responses in sports (such as basketball) characterized by sprints (accelerations/decelerations) and changes of direction.

Purpose:

To determine the energy cost (C) of shuttle runs with different turning angles and over different distances (with different acceleration/deceleration patterns).

Methods:

Nine basketball players were asked to complete 6 intermittent tests over different distances (5, 10, 25 m) and with different changes of direction (180° at 5 and 25 m; 0°, 45°, 90°, and 180° at 10 m) at maximal speed (v ≍ 4.5 m/s), each composed by 10 shuttle runs of 10-s duration and 30-s recovery; during these runs oxygen uptake (VO2), blood lactate (Lab), and C were determined.

Results:

For a given shuttle distance (10 m) no major differences where observed in VO2 (~33 mL · min−1 · kg−1), Lab (~3.75 mM), and C (~21.2 J · m−1 · kg−1) when the shuttle runs were performed with different turning angles. For a given turning angle (180°), VO2 and Lab were found to increase with the distance covered (VO2 from 26 to 35 mL · min−1 · kg−1; Lab from 0.7 to 7.6 mM) while C was found to decrease with it (from 29.9 to 10.6 J · m−1 · kg−1); the relationship between C and d (m) is well described by C = 92.99 × d 0.656, R 2 = .971.

Conclusions:

The metabolic demands of shuttle tests run at maximal speeds can be estimated based on the running distance, while the turning angle plays a minor role in determining C.

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Stephen Seiler and Øystein Sylta

The purpose of this study was to compare physiological responses and perceived exertion among well-trained cyclists (n = 63) performing 3 different high-intensity interval-training (HIIT) prescriptions differing in work-bout duration and accumulated duration but all prescribed with maximal session effort. Subjects (male, mean ± SD 38 ± 8 y, VO2peak 62 ± 6 mL · kg–1 · min–1) completed up to 24 HIIT sessions over 12 wk as part of a training-intervention study. Sessions were prescribed as 4 × 16, 4 × 8, or 4 × 4 min with 2-min recovery periods (8 sessions of each prescription, balanced over time). Power output, HR, and RPE were collected during and after each work bout. Session RPE was reported after each session. Blood lactate samples were collected throughout the 12 wk. Physiological and perceptual responses during >1400 training sessions were analyzed. HIIT sessions were performed at 95% ± 5%, 106% ± 5%, and 117% ± 6% of 40-min time-trial power during 4 × 16-, 4 × 8-, and 4 × 4-min sessions, respectively, with peak HR in each work bout averaging 89% ± 2%, 91% ± 2%, and 94% ± 2% HRpeak. Blood lactate concentrations were 4.7 ± 1.6, 9.2 ± 2.4, and 12.7 ± 2.7 mmol/L. Despite the common prescription of maximal session effort, RPE and sRPE increased with decreasing accumulated work duration (AWD), tracking relative HR. Only 8% of 4 × 16-min sessions reached RPE 19–20, vs 61% of 4 × 4-min sessions. The authors conclude that within the HIIT duration range, performing at “maximal session effort” over a reduced AWD is associated with higher perceived exertion both acutely and postexercise. This may have important implications for HIIT prescription choices.