Effect of Footwear on the Biomechanics of Loaded Back Squats to Volitional Exhaustion in Skilled Lifters

Excessive rearfoot motion, especially in the frontal plane, is believed to be a major cause of overload injuries in running. The aim of this study was to determine the influence of fatigue on frontal rearfoot motion just before volitional abandonment during an exhaustive run on a treadmill. Rearfoot kinematics were recorded three-dimensionally and reconstructed in a frontal plane associated with the heel. Statistical analysis of the results suggested that exhaustion did not influence tibial varum substantially, except at first heel strike. However, maximal calcaneal eversion and subtalar pronation did increase significantly, while maximal pronation velocity accelerated to 100°/s more than at the start of the exhaustive run. Also, the results of this study suggest that the increase in rearfoot motion is directly affected by fatigue and not by a fatigue-induced increase in step length.

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Verification phase as a useful tool in the determination of the maximal oxygen uptake of distance runners

Applied Physiology Nutrition and Metabolism ◽

10.1139/h06-023 ◽

2006 ◽

Vol 31 (5) ◽

pp. 541-548 ◽

Cited By ~ 53

Author(s):

Adrian W. Midgley ◽

Lars R. McNaughton ◽

Sean Carroll

Keyword(s):

Heart Rate ◽

Oxygen Uptake ◽

Maximal Oxygen Uptake ◽

Peak Oxygen Uptake ◽

Treadmill Running ◽

Distance Runners ◽

Peak Heart Rate ◽

Incremental Test ◽

Volitional Exhaustion

This study investigated the utility of a verification phase for increasing confidence that a “true” maximal oxygen uptake had been elicited in 16 male distance runners (mean age (±SD), 38.7 (± 7.5 y)) during an incremental treadmill running test continued to volitional exhaustion. After the incremental test subjects performed a 10 min recovery walk and a verification phase performed to volitional exhaustion at a running speed 0.5 km·h–1 higher than that attained during the last completed stage of the incremental phase. Verification criteria were a verification phase peak oxygen uptake ≤ 2% higher than the incremental phase value and peak heart rate values within 2 beats·min–1 of each other. Of the 32 tests, 26 satisfied the oxygen uptake verification criterion and 23 satisfied the heart rate verification criterion. Peak heart rate was lower (p = 0.001) during the verification phase than during the incremental phase, suggesting that the verification protocol was inadequate in eliciting maximal values in some runners. This was further supported by the fact that 7 tests exhibited peak oxygen uptake values over 100 mL·min–1 (≥ 3%) lower than the peak values attained in the incremental phase. Further research is required to improve the verification procedure before its utility can be confirmed.

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Exercise performance after ventilatory work

Journal of Applied Physiology ◽

10.1152/jappl.1982.52.6.1581 ◽

1982 ◽

Vol 52 (6) ◽

pp. 1581-1585 ◽

Cited By ~ 34

Author(s):

B. Martin ◽

M. Heintzelman ◽

H. I. Chen

Keyword(s):

Vital Capacity ◽

Minute Ventilation ◽

Forced Expiratory Volume ◽

Muscle Endurance ◽

O2 Uptake ◽

Short Term ◽

Running Performance ◽

Volitional Exhaustion ◽

Ventilatory Muscles

Although increased ventilation is one of the most readily observed physiological responses to exercise, it is uncertain how severely this hyperpnea stresses the ventilatory muscles. As one approach to this question, we compared short-term maximal running performance in nine subjects with and without prior ventilatory work designed to reduce ventilatory muscle endurance. This work consisted of 150 min of sustained maximum ventilation performed isocapnically while the subjects were seated. Both the level of sustained expired minute ventilation and the O2 uptake associated with it slowly declined with time during this 150-min period. On the average, subjects were able to maintain two-thirds of their 12-s maximum voluntary ventilation (MVV) during this long-term breathing test. The test had no effect on subsequently measured vital capacity, forced expiratory volume in 1 s, or the MVV. However, in short-term maximal running, at constant speed upgrades increased 1% each minute until volitional exhaustion, performance after prior breathing work was reduced as compared with control (6.5 vs. 7.6 min; P less than 0.01). Subjects ceased work at significantly lower ventilation (117 vs. 124 1.min-1 BTPS; P less than 0.05) and heart rate (179 vs. 187 beats.min-1; P less than 0.01) and reached significantly lower peak O2 uptake (3.07 vs. 3.24 1.min-1 STPD; P less than 0.05) during maximal running after ventilatory work. We conclude that reduced ventilatory muscle endurance alone is sufficient to decrease short-term maximal running performance.

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P6341Impact of left-ventricular hemodynamics on treadmill exercise intolerance in conscious rats: pilot evaluation in animals with diastolic dysfunction

European Heart Journal ◽

10.1093/eurheartj/ehz746.0938 ◽

2019 ◽

Vol 40 (Supplement_1) ◽

Author(s):

B S Ferguson ◽

N Bennett ◽

C Zambataro ◽

R Shimkunas ◽

C L Del Rio

Keyword(s):

Heart Rate ◽

Blood Glucose ◽

Diastolic Dysfunction ◽

Exercise Capacity ◽

Acute Exercise ◽

Left Ventricular ◽

Treadmill Running ◽

Exercise Intolerance ◽

Volitional Exhaustion

Abstract Introduction Exercise intolerance is a clinical hallmark of patients with hypertrophic cardiomyopathy and/or impaired diastolic function. Elevated LV filling pressures, particularly in response to acute exercise bouts, are thought to play a role limiting exercise capacity in ventricles with abnormal relaxation/compliance. However, it is experimentally difficult to obtain in vivo hemodynamic measures necessary for the evaluation of centrally mediated dysfunction. Leveraging radio-telemetry, we evaluated central hemodynamic parameters as mediators of exercise intolerance in obese ZSF1 rats with diabetes, hypertension, and diastolic dysfunction. Methods Both ZSF1 (637+12g, n=8) and age-matched (28 weeks) healthy control (CTRL, 543+14g, n=4, P<0.05) rats were instrumented for telemetric left-ventricular pressure (LVP) recordings. Following surgical recovery rats were familiarized to treadmill running and subsequently challenged with an exercise protocol aimed at increasing heart rate by 200 beats/min (5° incline, 15 m/min, increased by 3 m/min every 2-min) until volitional exhaustion. LV pressures were collected continuously during cage resting, treadmill resting, and post-exercise until heart rate returned to baseline. Additionally, resting echocardiographic and blood glucose measures were collected. Results At rest, ZSF1 rats had preserved ejection fraction (73+6 vs 79+9%), elevated (P<0.05) blood glucose (237+83 vs 94+23 mg/dL), end-systolic (147+18 vs 103+13 mmHg), and end-diastolic pressures (16+3 vs 9+3 mmHg), with preserved indexed end-diastolic volumes (670+95 vs 741+89 μL/kg), suggesting impaired diastolic compliance. ZSF1 rats terminated exercise prematurely (8:26+1:20 vs 10:27+1:18 min, P<0.05), indicating a limitation in exercise capacity. This early volitional exhaustion was noted while end-diastolic pressures were not further increased (17+7 mmHg), suggesting that other pathological derangement may play a role modulating exercise capacity. For instance, ZSF1 rats tended to have a blunted increase in the systolic index dP/dt40 (+2589+1450 vs +3938+749 mmHg/s, P<0.1) despite achieving comparable increases in HR (193+34 vs 196+38 bpm) with exercise. Conclusion This pilot study demonstrates the feasibility for evaluation of left-ventricular hemodynamics during exercise in rodents with diastolic dysfunction, establishing a platform to evaluate both the mechanisms of exercise intolerance as well as potential therapeutic approaches to rescue exercise capacity. Acknowledgement/Funding MyoKardia

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Reproducibility of Physiological and Performance Measures from a Squash-Specific Fitness Test

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.4.1.41 ◽

2009 ◽

Vol 4 (1) ◽

pp. 41-53 ◽

Cited By ~ 7

Author(s):

Michael Wilkinson ◽

Damon Leedale-Brown ◽

Edward M. Winter

Keyword(s):

Heart Rate ◽

Oxygen Uptake ◽

Lactate Threshold ◽

Physiological Responses ◽

Lactate Concentration ◽

Maximum Heart Rate ◽

Fitness Test ◽

Performance Time ◽

Volitional Exhaustion ◽

And Performance

Purpose:We examined the reproducibility of performance and physiological responses on a squash-specific incremental test.Methods:Eight trained squash players habituated to procedures with two prior visits performed an incremental squash test to volitional exhaustion on two occasions 7 days apart. Breath-by-breath oxygen uptake ( Vo2) and heart rate were determined continuously using a portable telemetric system. Blood lactate concentration at the end of 4-min stages was assessed to determine lactate threshold. Once threshold was determined, test speed was increased every minute until volitional exhaustion for assessment of maximal oxygen uptake (Vo2max), maximum heart rate (HRmax), and performance time. Economy was taken as the 60-s mean of Vo2 in the final minute of the fourth stage (below lactate threshold for all participants). Typical error of measurement (TEM) with associated 90% confidence intervals, limits of agreement, paired sample t tests, and least products regression were used to assess the reproducibility of scores.Results:Performance time (TEM 27 s, 4%, 90% CI 19 to 49 s) Vo2max (TEM 2.4 mL·kg−1·min−1, 4.7%, 90% CI 1.7 to 4.3 mL·kg−1·min−1), maximum heart rate (TEM 2 beats·min−1, 1.3%, 90% CI 2 to 4 beats·min−1), and economy (TEM 1.6 mL·kg−1·min−1, 4.1%, 90% CI 1.1 to 2.8 mL·kg−1·min−1) were reproducible.Conclusions:The results suggest that endurance performance and physiological responses to a squash-specific fitness test are reproducible.

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Open-ended time durations for stationary start intense cycle ergometer exercise testing

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2012-0270 ◽

2013 ◽

Vol 38 (5) ◽

pp. 574-580

Author(s):

Dawn Marie Klopp ◽

Nicole Theresa Vargas ◽

Robert Andrew Robergs

Keyword(s):

Body Mass ◽

Peak Power ◽

Cycle Ergometry ◽

Stepwise Multiple Regression ◽

Test Duration ◽

Measured Variable ◽

Time To Peak ◽

Volitional Exhaustion ◽

Mass Load ◽

Ergometer Exercise

The study involved application of different applied loads to measure altered test durations, time to peak power, peak power, and peak cadence during intense cycle ergometry exercise. Healthy, physically active male (n = 11) and female (n = 11) subjects (18–45 years) performed the following 3 bouts of intense cycle ergometry at peak cadence to volitional exhaustion on 3 separate days, 48 h to 1 week apart: (i) 85 g·kg−1 body mass load; (ii) 75 g·kg−1 body mass load; and (iii) 100 g·kg−1 body mass load. Trials (ii) and (iii) were performed in random order after trial (i). Exercise consisted of a stationary start, where test termination occurred when cadence decreased to <35 r·min−1. Mean (±SD) for gender main effects for time to peak power were 7.64 ± 2.76 vs. 9.49 ± 2.76 s (p < 0.001) for males and females, respectively. Relative peak power data for males vs. females for 75, 85, and 100 g·kg−1 were 10.01 ± 1.371 vs. 7.81 ± 1.25, 10.16 ± 1.61 vs. 7.67 ± 1.35, and 10.91 ± 2.03 vs. 7.31 ± 1.37 W·kg−1, respectively. The means for test duration for the GENDER × LOAD interaction (p = 0.09) were 68.25 ± 17.80 vs. 56.5 ± 11.56, 63.70 ± 17.21 vs.57.95 ± 10.45, and 51.99 ± 14.59 vs. 49.54 ± 12.45 s for males vs. females for each of 75, 85, and 100 g·kg−1, respectively. Stepwise multiple regression involving load and gender resulted in an explanation of variance (R2) of only 31.2%. Open-ended testing should be performed at a load of 100 g·kg−1 body mass for males and 85 g·kg−1 body mass females, causing volitional exhaustion in approximately 60 s and should allow test duration to be another measured variable.

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Accuracy of W′ Recovery Kinetics in High Performance Cyclists—Modeling Intermittent Work Capacity

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2017-0034 ◽

2018 ◽

Vol 13 (6) ◽

pp. 724-728 ◽

Cited By ~ 7

Author(s):

Jason C. Bartram ◽

Dominic Thewlis ◽

David T. Martin ◽

Kevin I. Norton

Keyword(s):

Recovery Rate ◽

High Performance ◽

Critical Power ◽

Intermittent Exercise ◽

Work Capacity ◽

Confidence Limits ◽

Volitional Exhaustion ◽

The Difference ◽

Effective Use ◽

Elite Cyclists

Purpose: With knowledge of an individual’s critical power and W′, the SKIBA 2 model provides a framework with which to track W′ balance during intermittent high-intensity work bouts. There are fears that the time constant controlling the recovery rate of W′ (τW′) may require refinement to enable effective use in an elite population. Methods: Four elite endurance cyclists completed an array of intermittent exercise protocols to volitional exhaustion. Each protocol lasted approximately 3.5–6 min and featured a range of recovery intensities, set in relation to the athlete’s critical power (DCP). Using the framework of the SKIBA 2 model, the τW′ values were modified for each protocol to achieve an accurate W′ at volitional exhaustion. Modified τW′ values were compared with equivalent SKIBA 2 τW′ values to assess the difference in recovery rates for this population. Plotting modified τW′ values against DCP showed the adjusted relationship between work rate and recovery rate. Results: Comparing modified τW′ values against the SKIBA 2 τW′ values showed a negative bias of 112 (46) s (mean ± 95% confidence limits), suggesting that athletes recovered W′ faster than predicted by SKIBA 2 (P = .0001). The modified τW′–DCP relationship was best described by a power function: τW′ = 2287.2 × DCP–0.688 (R2 = .433). Conclusions: The current SKIBA 2 model is not appropriate for use in elite cyclists, as it underpredicts the recovery rate of W′. The modified τW′ equation presented will require validation but appears more appropriate for high-performance athletes. Individual τW′ relationships may be necessary to maximize the model’s validity.

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Insufficient control of exercise intensity by heart rate monitoring in cardiac patients

European Journal of Preventive Cardiology ◽

10.1177/1741826711406832 ◽

2011 ◽

Vol 19 (3) ◽

pp. 436-443 ◽

Cited By ~ 2

Author(s):

Falko Frese ◽

Philipp Seipp ◽

Susanne Hupfer ◽

Peter Bärtsch ◽

Birgit Friedmann-Bette

Keyword(s):

Heart Rate ◽

Cardiac Rehabilitation ◽

Exercise Intensity ◽

Cardiac Patients ◽

Treadmill Test ◽

Exercise Tests ◽

Self Monitoring ◽

Volitional Exhaustion ◽

Pulse Palpation ◽

Treadmill Testing

Objectives: To test the reliability of heart rate (HR) recommendations for cardiac rehabilitation training obtained from different treadmill tests. Background: For training in cardiac rehabilitation, HR recommendations are derived from cardio-pulmonary tests. Exercise intensity is often controlled through self-monitoring HR by the cardiac patients. Design: Non-randomized clinical trial. Methods: 25 patients of a cardiac sports group (six women, 19 men, age 68.3 ± 5 years, height 171 ± 10 cm, weight 82 ± 12.8 kg) performed a stepwise increasing treadmill test according to a modified Stanford protocol (S) and a ramp treadmill test according to the Balke–Ware protocol (B) until volitional exhaustion. In 16 patients, HR was assessed with a HR monitor and compared with HR obtained by self-monitoring through pulse palpation during three training sessions. Results: Similar peak cardiopulmonary responses were obtained with the two exercise protocols of significantly ( p < 0.001) different duration (S 22:05 ± 7:11 min, B 13:31 ± 4:20 min). During the training sessions, HR exceeded the upper HR limit set at 85% HRpeak in 15 patients and in nine patients, higher HRpeak than in the exercise tests was observed. Five participants did not accurately measure their HR by pulse palpation. Conclusions: All but one patient of the cardiac sports group did not adhere to the HR recommendations derived from incremental treadmill testing, most likely because volitional exhaustion occurred in both treadmill tests before maximal cardiopulmonary responses were reached. In about 30% of the patients, training intensity could not be controlled by self-monitoring because of inaccurate pulse palpation.

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NEAR-INFRARED MONITORING OF THE LUMBAR ERECTOR SPINAE MUSCLE IN HEALTHY MEN AND WOMEN DURING STATIC AND DYNAMIC ENDURANCE WORK

Journal of Innovative Optical Health Sciences ◽

10.1142/s1793545811001381 ◽

2011 ◽

Vol 04 (02) ◽

pp. 173-182 ◽

Cited By ~ 2

Author(s):

RAMMOHAN V. MAIKALA ◽

YAGESH N. BHAMBHANI

Keyword(s):

Infrared Spectroscopy ◽

Near Infrared Spectroscopy ◽

Near Infrared ◽

Erector Spinae ◽

Arm Cranking ◽

Static Test ◽

Physiological Limits ◽

Volitional Exhaustion ◽

Lumbar Muscle ◽

Trunk Extension

Understanding muscle hemodynamics using near-infrared spectroscopy is increasingly evident in the recent spinal disorders-related literature. However, none of these human studies addressed the issue of physiological limits for the lumbar muscle within the same participants during various exercise modes. The purpose of this study is to evaluate physiological limits for the lumbar muscle during dynamic and static endurance tests. On three separate days, 22 healthy men and women performed three endurance protocols (static prone trunk extension, arm cranking, and pushing–pulling) until volitional exhaustion. For each protocol, minimum and maximum oxygenation and blood volume responses from the right lumbar erector spinae were obtained using a continuous dual wavelength near-infrared spectroscopy (Micro-Runman, NIM Inc., PA, USA). Statistical analysis showed that greatest reduction in oxygenation (minimum) were obtained during dynamic exercises: pushing–pulling (2.1 times) and arm cranking (2.03 times) versus static test (P < 0.05). Physiological change (calculated as the difference between maximum during recovery and minimum at the point of volitional exhaustion) during static test was lower [(66–75% for oxygenation) and (34–46% for blood volume)] than dynamic exercises (P < 0.05). Contrary to the theory that sufficient occlusion of blood flow to the lumbar muscle is possible with static trunk extension, it was concluded that a dynamic protocol until volitional exhaustion might be a good alternative in establishing near-infrared spectroscopy-derived physiological limits to the lumbar muscle. Further research is essential to identify an optimal calibration procedure for establishing true hypoxic values for the human lumbar muscle.

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