Effects of Base Line Changes in Work Rate on Cardiorespiratory Dynamics in Incremental and Decremental Ramp Exercise

1995 ◽  
pp. 159-164 ◽  
Author(s):  
Tatsuhisa Takahashi ◽  
Kyuichi Niizeki ◽  
Yoshimi Miyamoto
Keyword(s):  
Work Rate ◽  
Base Line ◽  
Ramp Exercise

Exercise efficiency: validity of base-line subtractions

1980 ◽  
Vol 48 (3) ◽  
pp. 518-522 ◽  
Author(s):  
W. N. Stainbsy ◽  
L. B. Gladden ◽  
J. K. Barclay ◽  
B. A. Wilson
Keyword(s):  
Energy Storage ◽  
Energy Expenditure ◽  
Work Rate ◽  
Published Data ◽  
Base Line ◽  
External Work ◽  
Future Studies ◽  
Using Data ◽  
Exercise Efficiency ◽  
Adequate Analysis

In evaluating the efficiency of humans performing exercise, base-line subtractions have been used in an attempt to determine the efficiency of the muscles in performing the external work. Despite the fact that base lines have been criticized previously, they have been widely used without adequate analysis of the implications involved. Calculations of efficiencies using data available in the literature for isolated muscle preparations revealed that base-line subtractions result in unreasonably high efficiencies. This suggests strongly that the base lines are invalid. To be valid, a base line must continue unchanged under all the conditions in which it is applied. Previously published data indicate clearly that exercise base lines change with increasing work rate and are therefore invalid. The use of base lines is further complicated by elastic energy storage in some types of exercise. Although exercise efficiencies using base line subtractions may be useful, they do not indicate muscle efficiency. Perhaps future studies of exercise metabolism should be directed less at refining base lines and more toward describing and quantifying the determinants of energy expenditure.

scholarly journals Establishing the V̇o2 versus constant-work-rate relationship from ramp-incremental exercise: simple strategies for an unsolved problem

2019 ◽  
Vol 127 (6) ◽  
pp. 1519-1527 ◽  
Author(s):  
Danilo Iannetta ◽  
Rafael de Almeida Azevedo ◽  
Daniel A. Keir ◽  
Juan M. Murias
Keyword(s):  
Lactate Threshold ◽  
Unsolved Problem ◽  
Critical Power ◽  
Work Rate ◽  
Incremental Exercise ◽  
Mean Response Time ◽  
Constant Work Rate ◽  
Ramp Exercise ◽  
The Mean ◽  
Highly Correlated

The dissociation between constant work rate of O2 uptake (V̇o2) and ramp V̇o2 at a given work rate might be mitigated during slowly increasing ramp protocols. This study characterized the V̇o2 dynamics in response to five different ramp protocols and constant-work-rate trials at the maximal metabolic steady state (MMSS) to characterize 1) the V̇o2 gain (G) in the moderate, heavy, and severe domains, 2) the mean response time of V̇o2 (MRT), and 3) the work rates at lactate threshold (LT) and respiratory compensation point (RCP). Eleven young individuals performed five ramp tests (5, 10, 15, 25, and 30 W/min), four to five time-to-exhaustions for critical power estimation, and two to three constant-work-rate trials for confirmation of the work rate at MMSS. G was greatest during the slowest ramp and progressively decreased with increasing ramp slopes (from ~12 to ~8 ml·min−1·W−1, P < 0.05). The MRT was smallest during the slowest ramp slopes and progressively increased with faster ramp slopes (1 ± 1, 2 ± 1, 5 ± 3, and 10 ± 4, 15 ± 6 W, P < 0.05). After “left shifting” the ramp V̇o2 by the MRT, the work rate at LT was constant regardless of the ramp slope (~150 W, P > 0.05). The work rate at MMSS was 215 ± 55 W and was similar and highly correlated with the work rate at RCP during the 5 W/min ramp ( P > 0.05, r = 0.99; Lin’s concordance coefficient = 0.99; bias = −3 W; root mean square error = 6 W). Findings showed that the dynamics of V̇o2 (i.e., G) during ramp exercise explain the apparent dichotomy existing with constant-work-rate exercise. When these dynamics are appropriately “resolved”, LT is constant regardless of the ramp slope of choice, and RCP and MMSS display minimal variations between each other. NEW & NOTEWORTHY This study demonstrates that the dynamics of V̇o2 during ramp-incremental exercise are dependent on the characteristics of the increments in work rate, such that during slow-incrementing ramp protocols the magnitude of the dissociation between ramp V̇o2 and constant V̇o2 at a given work rate is reduced. Accurately accounting for these dynamics ensures correct characterizations of the V̇o2 kinetics at ramp onset and allows appropriate comparisons between ramp and constant-work-rate exercise-derived indexes of exercise intensity.

The Work Rate Corresponding to Ventilatory Threshold During Steady-State and Ramp Exercise

2006 ◽  
Vol 1 (3) ◽  
pp. 222-232 ◽  
Author(s):  
Oliver Faude ◽  
Tim Meyer ◽  
Wilfried Kindermann
Keyword(s):  
Steady State ◽  
Time Delay ◽  
Ventilatory Threshold ◽  
Work Rate ◽  
Endurance Capacity ◽  
Mean Values ◽  
State Test ◽  
Ramp Exercise ◽  
The Difference ◽  
Steady State Test

Purpose:The work rate (WR) corresponding to ventilatory threshold (VT) is an appropriate intensity for regenerative and low-intensity training sessions. During incremental ramp exercise, VO2 increase lags behind WR increase. Traditionally, a VO2 time delay (td) of 45 seconds is used to calculate the WR at VT from such tests. Considerable inaccuracies were observed when using this constant td. Therefore, this study aimed at reinvestigating the temporal relationship between VO2 and WR at VT.Methods:20 subjects (VO2peak 49.9 to 72.6 mL · min–1 · kg–1) performed a ramp test in order to determine VT and a subsequent steady-state test during which WR was adjusted to elicit the VO2 corresponding to VT. The difference in WR and heart rate at VT was calculated between the ramp and the steady-state test (WRdiff, HRdiff) as well as the time delay corresponding to WRdiff during ramp exercise.Results:Mean values were td = 85 ± 26 seconds (range 38 to 144), WRdiff = 45 ± 12 W (range 23 to 67), HRdiff = 1 ± 9 beats/min (range –21 to +15). The limits of agreement for the difference between WR at VT during ramp and steady-state exercise were ± 24 W. No signifi cant influence on td, WRdiff, or HRdiff from differences in endurance capacity (VO2peak and VT; P > .10 for all correlations) or ramp increment (P = .26, .49, and .85, respectively) were observed.Conclusion:The wide ranges of td, WRdiff, and HRdiff prevent the derivation of exact training guidelines from single-ramp tests. It is advisable to perform a steady-state test to exactly determine the WR corresponding to VT.

Continuous increase in blood lactate concentration during different ramp exercise protocols

1989 ◽  
Vol 66 (3) ◽  
pp. 1104-1107 ◽  
Author(s):  
M. E. Campbell ◽  
R. L. Hughson ◽  
H. J. Green
Keyword(s):  
Blood Lactate ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Continuous Model ◽  
Work Rate ◽  
Transformation Model ◽  
Mean Square ◽  
Log Transformation ◽  
Ramp Exercise ◽  
The Mean

The applicability of a continuous model description of the blood lactate concentration [( La-]) vs. O2 uptake (VO2) relationship was studied in nine healthy male volunteers during three different ramp exercise protocols. The work rate was increased at either 8, 15, or 50 W/min. The continuous model for [La-] = a + b exp(cVO2) was compared statistically with a previously proposed log-log transformation model for the [La-] and VO2 variables. It was found that the mean square error was significantly less for the continuous as opposed to the log-log model (P less than 0.01) by analysis of variance pooled across all three ramp slopes. The mean square errors from the individual ramp slopes were also significantly less for the continuous model by paired t test (P less than 0.05). It was observed that the major contributor to the increased error of the log-log model was at VO2's at or above the intersection point (lactate threshold) of the two linear log-transformed segments. The log-log transformation does not appear to relate to any physiological process. The lactate slope index, taken as the point where the slope of the relationship between [La-] and VO2 (i.e., d[La-]/dVO2) equaled 1, occurred at a mean VO2 of 2.25 and 2.37 l/min for the 15- and 8-W/min ramp slopes, respectively, but at 2.76 l/min for the 50-W/min ramp (P less than 0.05). It is concluded that [La-] increases as a continuous function with respect to VO2 across a wide range of ramp work rate slopes.

Influence of muscle fibre type and pedal rate on the V?O2-work rate slope during ramp exercise

2004 ◽  
Vol 91 (2-3) ◽  
pp. 238-245 ◽  
Author(s):  
Andrew M. Jones ◽  
Iain T. Campbell ◽  
Jamie S. M. Pringle
Keyword(s):  
Muscle Fibre ◽  
Fibre Type ◽  
Work Rate ◽  
Muscle Fibre Type ◽  
Pedal Rate ◽  
Ramp Exercise

scholarly journals REPEATED BOUTS OF FAST RAMP EXERCISE ARE NOT ASSOCIATED WITH CHANGES IN THE VO2-WORK RATE SLOPE

2002 ◽  
Vol 34 (5) ◽  
pp. S154
Author(s):  
B W. Scheuermann ◽  
J S. Williams ◽  
J U. Gonzales ◽  
D Roh ◽  
T J. Barstow
Keyword(s):  
Work Rate ◽  
Ramp Exercise

Muscular efficiency during steady-rate exercise: effects of speed and work rate

1975 ◽  
Vol 38 (6) ◽  
pp. 1132-1139 ◽  
Author(s):  
G. A. Gaesser ◽  
G. A. Brooks
Keyword(s):  
Coupling Efficiency ◽  
Cycle Ergometer ◽  
Work Rate ◽  
Base Line ◽  
Exponential Relationship ◽  
Steady Rate ◽  
Resting Metabolism ◽  
Traditional Mode ◽  
Delta G ◽  
Male Subjects

In a comparison of traditional and theoretical exercise efficiency calculations male subjects were studied during steady-rate cycle ergometer exercises of “0,” 200, 400, 600, and 800 kgm/min while pedaling at 40, 60, 80, and 100 rpm. Gross (no base-line correction), net (resting metabolism as base-line correction), work (unloading cycling as base-line correction), and delta (measurable work rate as base-line correction) efficiencies were computed. The result that gross (range 7.5–20.4%) and net (9.8–24.1%) efficiencies increased with increments in work rate was considered to be an artifact of calculation. A LINEAR OR SLIGHTLY EXPONENTIAL RELATIONSHIP BETWEEN CALORIC OUTPUT AND WORK RATE DICTATES EITHER CONSTANT OR DECREASING EFFICIENCY WITH INCREMENTS IN WORK. The delta efficiency (24.4–34.0%) definition produced this result. Due to the difficulty in obtaining 0 work equivalents, the work efficiency definition proved difficult to apply. All definitions yielded the result of decreasing efficiency with increments in speed. Since the theoretical-thermodynamic computation (assuming mitochondrial P/O = 3.0 and delta G = -11.0 kcal/mol for ATP) holds only for CHO, the traditional mode of computation (based upon VO2 and R) was judged to be superior since R less than 1.0. Assuming a constant phosphorylative-coupling efficiency of 60%, the mechanical contraction-coupling efficiency appears to vary between 41 and 57%.

Exercise efficiency during arm ergometry: effects of speed and work rate

1984 ◽  
Vol 56 (2) ◽  
pp. 495-499 ◽  
Author(s):  
S. K. Powers ◽  
R. E. Beadle ◽  
M. Mangum
Keyword(s):  
Energy Expenditure ◽  
Power Output ◽  
Resting Metabolic Rate ◽  
Open Circuit ◽  
Work Rate ◽  
Curvilinear Relationship ◽  
Base Line ◽  
Gross Efficiency ◽  
The Difference ◽  
Power Outputs

The purpose of this investigation was to determine the effects of increasing work rate and speed of movement on efficiency during steady-state arm crank ergometry (ACE). Ten men exercised at speeds of 50, 70, and 90 rpm and four power outputs (15, 30, 45, and 60 W). O2 uptake determinations were made using open-circuit spirometry and energy expenditure was calculated from the respiratory exchange ratio. Gross (work accomplished/energy expended), work (unloaded cranking as base-line correction), and delta (measurable work as base-line correction) efficiencies were computed. A curvilinear relationship was found to exist between work rate and energy expenditure, which dictates that both delta and work efficiency will decrease with increments in work. Work (range 20–29%) and delta (range 14–30%) efficiencies decreased with increases in power output. The result that gross efficiency (range 6–15%) increased with increments in work was due to the decreasing effect of the resting metabolic rate on the total energy expended. Gross, work, and delta efficiencies were lower (P less than 0.05) at 90 rpm when compared with the same work rate at 50 and 70 rpm. Although all of the exercise efficiencies tended to be lower at 70 rpm compared with work at 50 rpm, the difference was significant (P less than 0.05) only at 45 and 60 W. These data suggest that delta and work efficiencies during ACE are decreased with increments in either speed or power output. However, gross efficiency increases as a function of power output but decreases as a function of speed of movement.

scholarly journals The relationship between muscle deoxygenation and activation in different muscles of the quadriceps during cycle ramp exercise

2011 ◽  
Vol 111 (5) ◽  
pp. 1259-1265 ◽  
Author(s):  
Lisa M. K. Chin ◽  
John M. Kowalchuk ◽  
Thomas J. Barstow ◽  
Narihiko Kondo ◽  
Tatsuro Amano ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Near Infrared ◽  
Vastus Lateralis ◽  
Young Male ◽  
Rectus Femoris ◽  
Work Rate ◽  
Sigmoid Function ◽  
Muscle Deoxygenation ◽  
Ramp Exercise ◽  
The Relationship

The relationship between muscle deoxygenation and activation was examined in three different muscles of the quadriceps during cycling ramp exercise. Seven young male adults (24 ± 3 yr; mean ± SD) pedaled at 60 rpm to exhaustion, with a work rate (WR) increase of 20 W/min. Pulmonary oxygen uptake was measured breath-by-breath, while muscle deoxygenation (HHb) and activity were measured by time-resolved near-infrared spectroscopy (NIRS) and surface electromyography (EMG), respectively, at the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM). Muscle deoxygenation was corrected for adipose tissue thickness and normalized to the amplitude of the HHb response, while EMG signals were integrated (iEMG) and normalized to the maximum iEMG determined from maximal voluntary contractions. Muscle deoxygenation and activation were then plotted as a percentage of maximal work rate (%WRmax). The HHb response for all three muscle groups was fitted by a sigmoid function, which was determined as the best fitting model. The c/d parameter for the sigmoid fit (representing the %WRmax at 50% of the total amplitude of the HHb response) was similar between VL (47 ± 12% WRmax) and VM (43 ± 11% WRmax), yet greater ( P < 0.05) for RF (65 ± 13% WRmax), demonstrating a “right shift” of the HHb response compared with VL and VM. The iEMG also showed that muscle activation of the RF muscle was lower ( P < 0.05) compared with VL and VM throughout the majority of the ramp exercise, which may explain the different HHb response in RF. Therefore, these data suggest that the sigmoid function can be used to model the HHb response in different muscles of the quadriceps; however, simultaneous measures of muscle activation are also needed for the HHb response to be properly interpreted during cycle ramp exercise.

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