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William McGarvey, Richard Jones and Stewart Petersen

The purpose of this investigation was to examine the effect of interval (INT) and continuous (CON) cycle exercise on excess post-exercise oxygen consumption (EPOC). Twelve males first completed a graded exercise test for VO2max and then the two exercise challenges in random order on separate days approximately 1 wk apart. The INT challenge consisted of seven 2 min work intervals at 90% VO2max, each followed by 3 min of relief at 30% VO2max. The CON exercise consisted of 30 to 32 min of continuous cycling at 65% VO2max. Gas exchange and heart rate (HR) were measured for 30 min before, during, and for 2 h post-exercise. Three methods were used to analyze post-exercise oxygen consumption and all produced similar results. There were no significant differences in either the magnitude or duration of EPOC between the CON and INT protocols. HR, however, was higher (P < 0.05) while respiratory exchange ratio (RER) was lower (P < 0.05) following INT. These results indicate that when total work was similar, the magnitude and duration of EPOC were similar following CON or INT exercise. The differences in HR and RER during recovery suggest differential physiological responses to the exercise challenges.

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Naiandra Dittrich, Ricardo Dantas de Lucas, Ralph Beneke and Luiz Guilherme Antonacci Guglielmo

The purpose of this study was to determine and compare the time to exhaustion (TE) and the physiological responses at continuous and intermittent (ratio 5:1) maximal lactate steady state (MLSS) in well-trained runners. Ten athletes (32.7 ± 6.9 y, VO2max 61.7 ± 3.9 mL · kg−1 · min−1) performed an incremental treadmill test, three to five 30-min constant-speed tests to determine the MLSS continuous and intermittent (5 min of running, interspaced by 1 min of passive rest), and 2 randomized TE tests at such intensities. Two-way ANOVA with repeated measures was used to compare the changes in physiological variables during the TE tests and between continuous and intermittent exercise. The intermittent MLSS velocity (MLSSint = 15.26 ± 0.97 km/h) was higher than in the continuous model (MLSScon = 14.53 ± 0.93 km/h), while the TE at MLSScon was longer than MLSSint (68 ± 11 min and 58 ± 15 min, P < .05). Regarding the cardiorespiratory responses, VO2 and respiratory-exchange ratio remained stable during both TE tests while heart rate, ventilation, and rating of perceived exertion presented a significant increase in the last portion of the tests. The results showed a higher tolerance to exercising during MLSScon than during MLSSint in trained runners. Thus, the training volume of an extensive interval session (ratio 5:1) designed at MLSS intensity should take into consideration this higher speed at MLSS and also the lower TE than with continuous exercise.

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Martin Buchheit, Bachar Haydar, Karim Hader, Pierre Ufland and Said Ahmaidi

Purpose:

To examine physiological responses to submaximal feld running with changes of direction (COD), and to compare two approaches to assess running economy (RE) with COD, ie, during square-wave (SW) and incremental (INC) exercises.

Methods:

Ten male team-sport athletes performed, in straight-line or over 20 m shuttles, one maximal INC and four submaximal SW (45, 60, 75 and 90% of the velocity associated with maximal pulmonary O2 uptake [vVO2pmax]). Pulmonary (VO2p) and gastrocnemius (VO2m) O2 uptake were computed for all tests. For both running mode, RE was estimated as the O2 cost per kilogram of bodyweight, per meter of running during all SW and INC.

Results:

Compared with straight-line runs, shuttle runs were associated with higher VO2p (eg, 33 ± 6 vs 37 ± 5 mL O2·min–1·kg–1 at 60%, P < .01) and VO2m (eg, 1.1 ± 0.5 vs 1.3 ± 0.8 mL O2·min–1·100 g–1 at 60%, P = .18, Cohen’s d = 0.32). With COD, RE was impaired during SW (0.26 ± 0.02 vs 0.24 ± 0.03 mL O2·kg–1·m–1, P < .01) and INC (0.23 ± 0.04 vs 0.16 ± 0.03 mL O2·kg–1·m–1, P < .001). For both SW and INC tests, the changes in RE with COD were related to height (eg, r = .56 [90%CL, 0.01;0.85] for SW) and weekly training/competitive volume (eg, r = –0.58 [–0.86;–0.04] for SW). For both running modes, RE calculated from INC was better than that from SW (both P < .001).

Conclusion:

Although RE is impaired during feld running with COD, team-sport players of shorter stature and/or presenting greater training/competitive volumes may present a lower RE deterioration with COD. Present results do not support the use of INC to assess RE in the feld, irrespective of running mode.

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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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Neil Armstrong

Purpose:

The presence of a maturational threshold that modulates children’s physiological responses to exercise training continues to be debated, not least due to a lack of longitudinal evidence to address the question. The purpose of this study was to investigate the interaction between swim-training status and maturity in nineteen trained (T, 10 ± 1 years, −2.4 ± 1.9 years prepeak height velocity, 8 boys) and fifteen untrained (UT, 10 ± 1 years, −2.3 ± 0.9 years prepeak height velocity, 5 boys) children, at three annual measurements.

Methods:

In addition to pulmonary gas exchange measurements, stroke volume (SV) and cardiac output (Q) were estimated by thoracic bioelectrical impedance during incremental ramp exercise.

Results:

At baseline and both subsequent measurement points, trained children had significantly (p < .05) higher peak oxygen uptake (year1 T 1.75 ± 0.34 vs. UT 1.49 ± 0.22; year 2 T 2.01 ± 0.31 vs. UT 1.65 ± 0.08; year 3 T 2.07 ± 0.30 vs. UT 1.77 ± 0.16 l min−1) and Q (year 1 T 15.0 ± 2.9 vs. UT 13.2 ± 2.2; year 2 T 16.1 ± 2.8 vs. UT 13.8 ± 2.9; year 3 T 19.3 ± 4.4 vs. UT 16.0 ± 2.7 l min−1). Furthermore, the SV response pattern differed significantly with training status, demonstrating the conventional plateau in UT but a progressive increase in T. Multilevel modeling revealed that none of the measured pulmonary or cardiovascular parameters interacted with maturational status, and the magnitude of the difference between T and UT was similar, irrespective of maturational status.

Conclusion:

The results of this novel longitudinal study challenge the notion that differences in training status in young people are only evident once a maturational threshold has been exceeded.

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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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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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Carlo Castagna, Lorenzo Francini, Susana C.A. Póvoas and Stefano D’Ottavio

Purpose:

To examine the acute effects of generic drills (running drills [RDs]) and specific (small-sided-games [SSGs]) long-sprint-ability (LSA) drills on internal and external load of male soccer players.

Methods:

Fourteen academy-level soccer players (mean ± SD age 17.6 ± 0.61 y, height 1.81 ± 0.63 m, body mass 69.53 ± 4.65 kg) performed four 30-s LSA bouts for maintenance (work:rest 1:2) and production (1:5) with RDs and SSGs. Players’ external load was tracked with GPS technology (20-Hz), and heart rate (HR), blood lactate concentration (BLc), and rating of perceived exertion (RPE) were used to characterize players’ internal load. Individual peak BLc was assessed with a 30-s all-out test on a nonmotorized treadmill (NMT).

Results:

Compared with SSGs, the RDs had a greater effect on external load and BLc (large and small, respectively). During SSGs players covered more distance with high-intensity decelerations (moderate to small). Muscular RPE was higher (small to large) in RDs than in SSGs. The production mode exerted a moderate effect on BLc while the maintenance condition elicited higher cardiovascular effects (small to large).

Conclusion:

The results of this study showed the superiority of generic over specific drills in inducing LSA-related physiological responses. In this regard production RDs showed the higher postexercise BLc. Individual peak blood lactate responses were found after the NMT 30-s all-out test, suggesting this drill as a valid option to RDs. The practical physiological diversity among the generic and specific LSA drills here considered enable fitness trainers to modulate prescription of RD and SSG drills for LSA according to training schedule.

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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.