High-intensity Cycle Ergometer Exercise Research Articles

Anaerobic Performance in Obese Populations: Underestimation of Power Profiles

We read with interest the article recently published in the September issue of the Asian Journal of Sports Medicine by Loenneke et al[1]. We were particularly interested in the section that stated; ‘The BIA device investigated in this study did not provide a valid estimate of fat free mass index (FFMI) in male and female collegiate athletes. Although there was a general tendency for the bioelectrical impedance analysis (BIA) to underestimate FFMI compared to DEXA, 98% of the estimates were within plus or minus 2 kg/m2. Therefore, while slightly biased, BIA may provide a reasonable (± 2 kg/m2) estimate of nutritional status for practitioners who are unable able to afford more expensive equipment’. In relation to the use of fat-free mass (FFM) as a correction factor in the study highlighted above, we would like to comment on the measurement of anaerobic ability in overweight and obese subjects using resistive forces derived from fat free mass (FFM) and total body mass (TBM). High intensity cycle ergometry has been widely employed to assess indices of muscle performance during maximal exercise. Traditionally, the resistive force established for such a test is determined from TBM multiplied by a ratio standard; e.g. 75g.kg-1 x TBM. McInnis and Balady [2] observed that individuals who weigh the same have very different body compositions that include variations in lean body mass and fat content. Van mil et al [3] recommended that optimal performance during high intensity cycle ergometry is highly related to an individual's FFM, or to the mass of the muscles that contribute to the test. Inbar et al [4] have suggested that fat-free mass or active muscle mass may provide a more realistic assessment of anaerobic ability during high intensity exercise performance. These statements agree with the earlier suggestions of Wilkie [5] who stated that resistive forces used during cycle ergometry should be matched as closely as possible to active muscle output. Body mass and not composition is the most commonly used index to determine resistive force selection during high intensity cycle ergometer exercise, and because power is the product of both resistive force and velocity, over or underestimations in power performance and assessment may occur. This may be particularly pronounced in overweight populations. Authors [6] investigated the anaerobic potential of an overweight and obese population using two resistive force selection procedures namely, TBM and FFM. The TBM resistive force protocol was inclusive of the fat component of body composition, whereas the FFM protocol was not. The study examined maximal exercise performance during friction braked cycle ergometry of 10 s duration. Subjects were assigned in a random order to either the TBM or FFM experimental condition. Eleven apparently healthy male university students (age 22.3 ± 2 yrs, body fat 27.1 ± 2%; determined hydrostatically) participated in the study (see Tables 1 and ​and2).2). Large significant differences (P<0.01) in peak power output (PPO) were found between the TBM and FFM experimental protocols (1029 ± 98 W TBM vs. 1397 ± 146 W FFM). The findings of the study indicated that greater peak power outputs were obtainable when resistive forces reflected FFM as opposed to TBM. These results have serious implications and relate to effective exercise prescription, diagnostic capacity, clinical examination and associated biochemistries in overweight and obese individuals. The findings also suggest that resistive force selection methods need to be reassessed, in obese and non-obese populations, when anaerobic ability is the diagnostic measure under investigation. Table 1 Subject Means (SD) for age and anthropometric characteristics (n = 11) Table 2 Means (SD*) for cycle ergometer test results (n = 11)

Short‐term sprint interval training increases insulin sensitivity in healthy adults but does not affect the thermogenic response to β‐adrenergic stimulation

Sprint interval training (SIT) and traditional endurance training elicit similar physiological adaptations. From the perspective of metabolic function, superior glucose regulation is a common characteristic of endurance-trained adults. Accordingly, we have investigated the hypothesis that short-term SIT will increase insulin sensitivity in sedentary/recreationally active humans. Thirty one healthy adults were randomly assigned to one of three conditions: (1) SIT (n = 12): six sessions of repeated (4-7) 30 s bouts of very high-intensity cycle ergometer exercise over 14 days; (2) sedentary control (n = 10); (3) single-bout SIT (n = 9): one session of 4 x 30 s cycle ergometer sprints. Insulin sensitivity was determined (hyperinsulinaemic euglycaemic clamp) prior to and 72 h following each intervention. Compared with baseline, and sedentary and single-bout controls, SIT increased insulin sensitivity (glucose infusion rate: 6.3 +/- 0.6 vs. 8.0 +/- 0.8 mg kg(1) min(1); mean +/- s.e.m.; P = 0.04). In a separate study, we investigated the effect of SIT on the thermogenic response to beta-adrenergic receptor (beta-AR) stimulation, an important determinant of energy balance. Compared with baseline, and sedentary and single-bout control groups, SIT did not affect resting energy expenditure (EE: ventilated hood technique; 6274 +/- 226 vs. 6079 +/- 297 kJ day(1); P = 0.51) or the thermogenic response to isoproterenol (6, 12 and 24 ng (kg fat-free mass)(1) min(1): %EE 11 +/- 2, 14 +/- 3, 23 +/- 2 vs. 11 +/- 1, 16 +/- 2, 25 +/- 3; P = 0.79). Combined data from both studies revealed no effect of SIT on fasted circulating concentrations of glucose, insulin, adiponectin, pigment epithelial-derived factor, non-esterified fatty acids or noradrenaline (all P > 0.05). Sixteen minutes of high-intensity exercise over 14 days augments insulin sensitivity but does not affect the thermogenic response to beta-AR stimulation.

Intake Of Water-soluble Protein During An Interval Of Repeated Strenuous Exercises Can Improve Serum Myoglobin Levels

Many athletes consume protein both immediately after exercise and before sleeping to build up the body and to recover from strenuous exercise. Little is known about the effects of protein supplementation during exercise because protein can have a bitter taste. Recently, athletes have been consuming a sports drink containing good tasting and rapidly absorbed water-soluble protein, without evidence of any obvious benefit. PURPOSE: To determine whether intake of water-soluble protein during exercise has a favorable effect on muscle damage, performance, and soreness. METHODS: Japanese trained male athletes (n=7) performed two sessions of high intensity cycle ergometer exercise. In each session, subjects did five repetitions of 10 s of maximal intensity riding interrupted by 50 s of resting. Subjects consumed protein (14.1 g/400 mL) either during exercise or immediately after exercise. Blood lactic acid, serum myoglobin, CK, and LDH were measured pre- and post-exercise. Perceived muscle soreness and psychological mood change (Profile of Mood State: POMS) were investigated. RESULTS: Serum myoglobin, CK, and LDH increased significantly 2 h after exercise. Intake of water-soluble protein during exercise (relative to protein intake after exercise) decreased myoglobin, CK, and LDH. POMS scores (fatigue, total scores) were also improved. CONCLUSIONS: In contrast to supplementation after exercise, supplementation during exercise attenuated post-exercise muscle damage and fatigue. The results suggest that ingestion of protein during exercise may be important.

Physiological, Biochemical and Mechanical Issues Relating to Resistive Force Selection During High-intensity Cycle Ergometer Exercise

High-intensity cycle ergometry of 30 seconds duration has been widely employed to assess indices of muscle performance during maximal exercise. Traditionally, the resistive force established for such a test is determined from total body mass (TBM) for a friction-loaded Monark cycle ergometer, i.e. 75 g·kg−1. More recent studies have shown that traditional forces may be too light to elicit maximal performances and that optimization protocols can produce higher peak power outputs. Conceptually, selecting the optimal resistive force according to TBM may not be the best approach. Fat-free mass or active muscle tissue may be a more preferable alternative. Because body mass, and not composition, is the most commonly used index to determine cycle ergometer resistive force, over-or underestimations in power calculations may occur. The aim of this paper is to outline friction-loaded cycle ergometer performance using resistive forces derived from TBM and fat-free mass, to quantify the upper body contribution to high-intensity cycle ergometry. A further aim is to outline mechanical issues related to cycle ergometer design and to quantify discrepancies in resistive force application.

Physiological Effects of Two Different Postactivation Potentiation Training Loads on Power Profiles Generated During High Intensity Cycle Ergometer Exercise

The purpose of this study was to investigate whether postactivation potentiation (PAP) would have any effect on high intensity cycle ergometer performance. Two different squatting exercises of different loads were presented in a random fashion prior to ergometric exercise. Seven male rugby players volunteered to participate in the study. There were no significant differences observed between peak power output (PPO) measurements for all three testing conditions (P > 0.05). There were also no differences recorded between mean power outputs (MPOs) and end power outputs (EPOs) (P > 0.05). The decrease in power output (FI %) also was found to be nonsignificant for all conditions (P > 0.05). The findings of this study indicate that performance of repeated heavy squats prior to a 30-second maximal cycle ergometer exercise did not improve the power profiles recorded and did not induce PAP at the time of testing.

Plasma Volume Response to 30-s Cycle Ergometry

It has been suggested that exercise-induced changes in plasma volume (PV) confound the interpretation of biochemical data obtained during the recovery period from exercise. No studies have sought to assess the effect of short-duration, high-intensity exercise on PV change and plasma lipid and lipoprotein concentrations. The purpose of this study was to compare power profiles, changes in PV, and plasma lipid and lipoprotein concentrations immediately after and 24 h after exercise. Subjects undertook two 30-s, high-intensity cycle ergometer protocols after optimization of resistive loads calculated from total body mass (TBM) and fat-free mass (FFM). Power output indices were recorded and blood samples were analyzed before, immediately after, and 24 h after exercise. Peak power outputs were significantly greater in FFM (1020+/-134 vs 953+/-114 W for FFM and TBM, respectively, P<0.05). No differences were found between TBM and FFM for mean power output, fatigue index, or work done. Significant decreases (P<0.05) in PV of 12.0+/-5.7 and 12.3+/-6.7% were recorded immediately after exercise for both TBM and FFM, respectively. At 24 h after exercise, a significant (P<0.05) increase in PV of 4.2+/-10.3% was recorded for TBM only. Significant increases (P<0.01) were recorded for serum triglyceride, cholesterol, HDL cholesterol, and LDL cholesterol immediately after exercise for both TBM and FFM. These increases disappeared when corrected for PV changes, with the exception of LDL cholesterol in TBM, which still displayed a significant increase compared with the preexercise values (2.50+/-0.74 mM (before) vs 2.72+/-0.84 mM (immediately after)). Our data show that short-duration, high-intensity cycle ergometer exercise tests can induce significant plasma volume decreases in untrained subjects, which may affect the interpretation of bloodborne biochemical parameters.

Changes in Blood Markers of Serotoninergic Activity Following High Intensity Cycle Ergometer Exercise

The purpose of this study was to measure concentrations of adrenaline (A), noradrenaline (NE), free tryptophan (f-Trp), prolactin (PRL), nonesterified fatty acids (NEFA), and blood lactate following 30 s of high-intensity cycle ergometer exercise. Adrenaline (A) and NE concentrations increased immediately postexercise (P < 0.05) and returned to levels observed at baseline 24 h later. Plasma f-Trp concentration decreased by 23.5% immediately following exercise (P < 0.05). There were no changes observed in serum concentrations of PRL. Plasma NEFA concentrations decreased immediately following exercise by 46% (P < 0.05) and returned to baseline values 24 h later. Whole blood lactate concentrations increased immediately post exercise (P < 0.05), and were higher than those measured 24 h later (P < 0.05). These findings indicate that blood markers of serotoninergic activity were unaltered by a single 30 s bout of maximal cycling.

Exercise training decreases ventilatory requirements and exercise-induced hyperinflation at submaximal intensities in patients with COPD: Chest 2005;128:2025–34.

Study objectives We hypothesized that endurance exercise training would reduce the degree of hyperinflation for a given level of exercise and thereby improve submaximal exercise endurance. Methods Twenty-four patients with COPD (mean FEV1, 36.4±8.5% of predicted [± sd ]) undertook a high-intensity cycle ergometer exercise training program for 45 min, three times a week for 7 weeks. Before and after training, the patients performed both an incremental exercise test to maximum and a constant work rate (CWR) test on a cycle ergometer at 75% of the peak work rate obtained in the pretraining incremental test. Ventilatory variables were measured breath-by-breath, and inspiratory capacity (IC) was measured every 2 min to assess changes in end-expiratory lung volume. Results After training, the increase in peak oxygen uptake was not statistically significant; however, the peak work rate increased by 12.9±10.3 W ( P 0.01 ). For the CWR test performed at the same work rate both before and after training, ventilation and breathing frequency (f) were lower after training (average, 1.97 L/min and 3.2 breaths/min, respectively; P 0.01 ) and IC was greater (by an average of 133 mL, P 0.05 ), signifying decreased hyperinflation. The increase in IC at the point of termination in the shortest CWR test for each individual (defined as isotime) correlated well with both the decreased f ( r = 0.63 , P = 0.001 ) and with the increase in CWR exercise endurance (average, 13.1 min, r = 0.46 , P = 0.023 ). Conclusions Exercise training in patients with severe COPD dramatically improves submaximal exercise endurance. Decreased dynamic hyperinflation may, in part, mediate the improvement in exercise endurance by delaying the attainment of a critically high inspiratory lung volume.

Exercise Training Decreases Ventilatory Requirements and Exercise-Induced Hyperinflation at Submaximal Intensities in Patients With COPD

We hypothesized that endurance exercise training would reduce the degree of hyperinflation for a given level of exercise and thereby improve submaximal exercise endurance. Twenty-four patients with COPD (mean FEV(1), 36.4 +/- 8.5% of predicted [+/- SD]) undertook a high-intensity cycle ergometer exercise training program for 45 min, three times a week for 7 weeks. Before and after training, the patients performed both an incremental exercise test to maximum and a constant work rate (CWR) test on a cycle ergometer at 75% of the peak work rate obtained in the pretraining incremental test. Ventilatory variables were measured breath-by-breath, and inspiratory capacity (IC) was measured every 2 min to assess changes in end-expiratory lung volume. After training, the increase in peak oxygen uptake was not statistically significant; however, the peak work rate increased by 12.9 +/- 10.3 W (p < 0.01). For the CWR test performed at the same work rate both before and after training, ventilation and breathing frequency (f) were lower after training (average, 1.97 L/min and 3.2 breaths/min, respectively; p < 0.01) and IC was greater (by an average of 133 mL, p < 0.05), signifying decreased hyperinflation. The increase in IC at the point of termination in the shortest CWR test for each individual (defined as isotime) correlated well with both the decreased f (r = 0.63, p = 0.001) and with the increase in CWR exercise endurance (average, 13.1 min, r = 0.46, p = 0.023). Exercise training in patients with severe COPD dramatically improves submaximal exercise endurance. Decreased dynamic hyperinflation may, in part, mediate the improvement in exercise endurance by delaying the attainment of a critically high inspiratory lung volume.

Catecholamine responses to high intensity cycle ergometer exercise: Body mass or body composition?

The purpose of this study was to compare the sympathoadrenergic and metabolic responses following 30 s of maximal high intensity cycle ergometry exercise when cradle resistive forces were derived from total-body mass (TBM) or fat-free mass (FFM). Increases in peak power output (PPO) and pedal velocity were recorded when resistive forces reflected FFM (953 +/- 114 W vs 1020 +/- 134 W; 134 +/- 8 rpm vs 141 +/- 7 rpm ; P < 0.05). No differences were observed between mean power output (MPO), fatigue index (FI%), work done (WD) or heart rate (HR) when the TBM and FFM protocols were compared. There were no differences between the TBM and FFM protocols for adrenaline (A), noradrenaline (NA) or blood lactate concentrations ([La-]B) recorded at rest, immediately post or 24 h post exercise. However, increases in blood concentrations of A and NA (P < 0.05) were recorded for both the TBM and FFM protocol immediately post exercise. Significant correlations (P < 0.05) were recorded between PPOs, immediate post- exercise NA and [La-]B for both the TBM and FFM protocols. [La-]B levels were also significantly elevated (P < 0.01) immediately post exercise for both the TBM and FFM protocols. The results from this study suggest that greater peak power outputs are obtainable with no subsequent differences in neurophysiological or metabolic stress as determined by plasma A, NA and [La-]B concentrations when resistive forces reflect FFM and not TBM during loading procedures. The findings also indicate that immediate post exercise concentrations return to resting levels 24 h post exercise.

The effect of glycogen depletion on the curvature constant parameter of the power-duration curve for cycle ergometry

For high-intensity cycle ergometer exercise, the relation between power (P) and its tolerable duration (t) has been well characterized by the hyperbolic relationship: (P-θF)t = W', or P = W'(1/t)+θF, where θF may be termed the ‘fatigue threshold’. The curvature constant (W') reflects a constant amount of work which is postulated to be equivalent to a finite energy store that relates to the oxygen-deficit: phosphagen pool, anaerobic glycolysis and oxygen stores. Compared to thetaF, the physiological nature of W' has received little consideration. The purpose of this study was therefore to establish the parameters of the power-duration curve (θF and W') for subjects in normal glycogen (NG) and glycogen depleted (GD) states. Seven healthy male subjects (aged 22 to 41 years) each performed four high-intensity square-wave exercise bouts on an electrically braked cycle ergometer under two different muscular glycogen content conditions, i.e. NG and GD states. Subjects performed the following exercise on the evening before the trial day to induce the GD state. Initially, they performed a 75-min cycling exercise at 60% of VO2max. After a 5-min rest period, they subsequently repeated a 1-min cycling bout at 115% of VO2max (separated by 1-min rest periods) until the subject could no longer maintain the prescribed pedal rate for the full minute. Subjects then reported to the laboratory after an overnight fast and performed a single high-intensity exercise bout. The GD procedure was repeated four times at 1-week intervals. In the GD state, the respiratory exchange ratio (RER) (VO2/VCO2) value during a recumbent control period prior to the trial was significantly lower than that in the NG state [GD: 0.84±0.02, NG: 0.94±0.04, mean±SD]. There was no significant difference for θF between GD and NG state [NG: 197.1±31.9 W, GD: 190.6±28.2 W]. W' in contrast was significantly reduced by the GD procedure [NG: 12.83±2.21 kJ, GD: 10.33±2.41 kJ]. The present results indicate that the muscular glycogen store seems to be an important determinant of the curvature constant (W') of the power-duration curve for cycle ergometry.

The effect of oral creatine supplementation on the curvature constant parameter of the power-duration curve for cycle ergometry in humans.

For high-intensity cycle ergometer exercise, the tolerable duration (t) is well characterized as a hyperbolic function of power output, P : t = W'/(P-thetaF), where thetaF may be termed the "fatigue threshold." The purpose of this study was to determine the effect of oral creatine (Cr) supplementation on the curvature constant parameter (W') of the power-duration curve. A double-blind research method and a cross-over design were employed for creatine/placebo supplementation. Eight healthy male subjects (aged 18 to 22 years) each performed four or five high-intensity square-wave exercise bouts on an electrically braked cycle ergometer after 5 d of Cr monohydrate (CR: 20 g of Cr with artificial sweetener/d) or placebo (PL: 6 g of glucose/d) supplementation. Each subject performed a single high-intensity exercise trial per day for four or five successive days to determination the P-t hyperbolic relation. After 6 weeks (the washout time of Cr from the muscles), each subject performed the other condition (i.e., PL or CR) and repeated the same experimental procedure. There was no significant difference for thetaF between PL and CR conditions (PL: 214.4 +/- 23.6, CR: 207.0 +/- 19.8 W, mean +/- SD). In contrast, W' was significantly increased by the Cr supplementation (PL: 10.9 +/- 2.7, CR: 13.7 +/- 3.0 kJ; p<0.05). The results indicated that Cr and/or PCr content in muscles seems to be one of the important determinants of the curvature constant parameter (W') of the power-duration hyperbolic curve for cycle ergometry.

Effect of the number of preceding muscle actions on subsequent peak power output

Many sports events require participants to exert a maximal effort in the closing stages - that is, after prior fatiguing exercise. Peak and mean pedalling rate during 30 s of high-intensity cycle ergometer exercise was manipulated by altering the applied resistance or the initial exercise intensity so that the effect of three contrasting strategies on subsequent peak power output could be examined. Seven female students cycled for 30 s in one of three conditions: (1) all-out effort against an applied resistance of 7.5% of body weight (test 1); (2) at a constant pace of 55% of the peak pedal rate of test 1 against a resistance of 10.9-0.4% of body weight (test 2); (3) all-out effort against the greater resistance (test 3). A 6 s sprint against the lesser resistance was performed 3 s after each test. Total work was greater (P < 0.01) in test 3 than in test 1, while mean pedal rate was higher (P < 0.01) in test 1 (mean- S.E.: 10.0-0.4 rad s -1 ) than in tests 2 and 3 (7.2-0.4 and 7.8-0.3 rad s -1 respectively). The peak power output in the subsequent 6 s sprint was similar following tests 2 and 3 (516-37 and 534-41 W respectively), but was lower following test 1 (420 -37 W) (P < 0.01, test 1 vs tests 2 and 3). These results indicate that the number of muscle actions during 30 s of fatiguing exercise may exert a considerable influence on one's ability to subsequently produce peak power output. In sports such as cycling where the same external velocity is attainable at different muscle action speeds, then appropriate gear selection during the race will impact on the rider's ability to sprint in the latter stages.

969 EFFECT OF PASSIVE AND ACTIVE RECOVERY ON THE RESYNTHESIS OF MUSCLE GLYCOGEN

The purpose of this investigation was to determine the effect of passive and active recovery on the resynthesis of muscle glycogen after high-intensity cycle ergometer exercise in untrained subjects. In a cross-over design, six college-aged males performed three, 1-min exercise bouts at approximately 130% VO2max with a 4-min rest period between each work bout. The exercise protocol for each trial was identical, while the recovery following exercise was either active (30 min at 40-50% VO2max, 30-min seated rest) or passive (60-min seated rest). Initial muscle glycogen values averaged 144.2 +/- 3.8 mmol.kg-1 w.w. for the active trial and 158.7 +/- 8.0 mmol.kg-1 w.w. for the passive trial. Corresponding immediate postexercise glycogen contents were 97.7 +/- 5.4 and 106.8 +/- 4.7 mmol.kg-1 w.w., respectively. These differences between treatments were not significant. However, mean muscle glycogen after 60 min of passive recovery increased 15.0 +/- 4.9 mmol.kg-1 w.w., whereas it decreased 6.3 +/- 3.7 mmol.kg-1 w.w. following the 60 min active recovery protocol (P < 0.05). Also, the decrease in blood lactate concentration during active recovery was greater than during passive recovery and significantly different at 10 and 30 min of the recovery period (P < 0.05). These data suggest that the use of passive recovery following intense exercise results in a greater amount of muscle glycogen resynthesis than active recovery over the same duration.

The effects of training on the metabolic and respiratory profile of high-intensity cycle ergometer exercise

The tolerable work duration (t) for high-intensity cycling is well described as a hyperbolic function of power (W): W = (W'.t-1) + Wa, where Wa is the upper limit for sustainable power (lying between maximum W and the threshold for sustained blood [lactate] increase, theta lac), and W' is a constant which defines the amount of work which can be performed greater than Wa. As training increases the tolerable duration of high-intensity cycling, we explored whether this reflected an alteration of Wa, W' or both. Before and after a 7-week regimen of intense interval cycle-training by healthy males, we estimated ( ) theta lac and determined maximum O2 uptake (mu VO2); Wa; W'; and the temporal profiles of pulmonary gas exchange, blood gas, acid-base and metabolic response to constant-load cycling at and above Wa. Although training increased theta lac (24%), mu VO2 (15%) and Wa (15%), W' was unaffected. For exercise at Wa, a steady state was attained for VO2, [lactate] and pH both pre- and post-training, despite blood [norepinephrine] and [epinephrine] ([NE], [E]) and rectal temperature continuing to rise. For exercise greater than Wa, there was a progressive increase in VO2 (resulting in mu VO2 at fatigue), [lactate], [NE], [E] and rectal temperature, and a progressive decrease for pH. We conclude that the increased endurance capacity for high-intensity exercise following training reflects an increased W asymptote of the W-t relationship with no effect on its curvature; consequently, there is no appreciable change in the amount of work which can be performed above Wa.(ABSTRACT TRUNCATED AT 250 WORDS)