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Excess Postexercise Oxygen Consumption is Unaffected by the Resistance and Aerobic Exercise Order in an Exercise Session
Abstract
The main purpose of this study was to compare the magnitude and duration of excess postexercise oxygen consumption (EPOC) after 2 exercise sessions with different exercise mode orders, resistance followed by aerobic exercise (R-A); aerobic by resistance exercise (A-R). Seven young men (19.6 ± 1.4 years) randomly underwent the 2 sessions. Aerobic exercise was performed on a treadmill for 30 minutes (80-85% of reserve heart rate). Resistance exercise consisted of 3 sets of 10 repetition maximum on 5 exercises. Previous to the exercise sessions, V(O2), heart rate, V(CO2), and respiratory exchange rate (RER) were measured for 15 minutes and again during recovery from exercise for 60 minutes. The EPOC magnitude was not significantly different between R-A (5.17 ± 2.26 L) and A-R (5.23 ± 2.48 L). Throughout the recovery period (60 minutes), V(O2) and HR values were significantly higher than those observed in the pre-exercise period (p < 0.05) in both exercise sessions. In the first 10 minutes of recovery, V(CO2) and RER declined to pre-exercise levels. Moreover, V(CO2) and RER values in A-R were significantly lower than in R-A. In conclusion, the main result of this study suggests that exercise mode order does not affect the EPOC magnitude and duration. Therefore, it is not necessary for an individual to consider the EPOC when making the decision as to which exercise mode is better to start a training session.
... On the other hand, regular aerobic exercise (AE) and resistance exercise (RE) have been recommended for different populations, given the positive effects in promoting health (1). Adopting these two types of training in a single exercise session is known as concurrent training (CT) (15,30), and the effects of altering the order of these activities in the session have not been fully clarified (2,22,30) when prescribing weight reduction exercises (9,20). ...
... One of the aspects that needs to be elucidated is the quantification of AE volume when it is controlled by calorie expenditure in the CT session. In general, the authors consider only the duration of the activity (22,30). However, the prescribed order of AE and RE in a CT session may affect calorie expenditure of the second activity. ...
... Although some studies have assessed the effects of concurrent exercises on EPOC (9,22,30) and PEH (11,18,29), none have controlled the volume of aerobic activity of a CT session by energy expenditure. Controlling the activity by the isocaloric method has the advantage of applying the same volume to the aerobic exercise, irrespective of the order of its execution during the session. ...
The purpose of this study was to determine, by means of isocaloric series of aerobic exercise, the influence of different concurrent training (CT) sequences exercises on cardiorespiratory responses during and after training sessions. Ten men (age, 27.8 ± 5.80 yrs) performed 2 CT sessions, aerobic exercise + resistance exercise (AE + RE) and resistance exercise + aerobic exercise (RE + AE) in counterbalanced order. Each subject underwent a cardiopulmonary exercise test using a treadmill and a 12 maximum repetitions test (12 RM). The AE was set at the speed corresponding to 70% VO2 reserve (VO2R) at an incline of 1%. RE was prescribed at 80% to 12 repetitions maximum (RM). Two-way ANOVA for repeated measures after sessions showed no intergroup difference for excessive post-exercise oxygen consumption (EPOC) (P=0.64), systolic blood pressure (SBP) (P=0.67), and diastolic blood pressure (DBP) (P=0.84). The paired t-test showed a difference in total energy expenditure (467 ± 24.9 kcal for AE + RE vs. 453 ± 30.9 kcal for RE + AE, P<0.01), but the duration of the AE + RE session was significantly longer (33 ± 2 min AE + RE vs. 28 ± 3 min RE + AE, P<0.01). These data suggest that alternating the order of AE and RE in a CT has no influence on EPOC and post-exercise hypotension (PEH), but when the AE was preceded by RE, less time was needed to obtain the same caloric expenditure. In this case, when the session was preceded by resistance exercises, less time was needed to obtain the calorie expenditure determined in the aerobic session.
... (10) The magnitude and time duration of EPOC is dependent on the individual's physical fitness level and on the intensity, duration, and mode of exercise. (11) Studies typically focus on how the mode of exercise affects EPOC, not on the how the type of recovery or any changes in the parasympathetic response may alter EPOC. In exercise recovery, the body will compensate for the increased need for oxygen by either increasing ventilations per minute or the volume of air inhaled with each breath. ...
... Metabolic data collected during the entire exercise portion were averaged over the 30-minute session. As previously reported by Oliveria et al., (11) the subject completed a 24-hour fast from caffeine and alcohol as well as a 12-hour fast from food prior to EPOC data collection. Initial recovery metabolic data and HR were collected for an additional 10 minutes immediately postexercise with the subject lying in a supine position. ...
Introduction:
Postexercise massage can be used to help promote recovery from exercise on the cellular level, as well as systemically by increasing parasympathetic activity. No studies to date have been done to assess the effects of massage on postexercise metabolic changes, including excess postexercise oxygen consumption (EPOC). The purpose of this study was to compare the effects of massage recovery and resting recovery on a subject's heart rate variability and selected metabolic effects following a submaximal treadmill exercise session.
Methods:
One healthy 24-year-old female subject performed 30 minutes of submaximal treadmill exercise prior to resting or massage recovery sessions. Metabolic data were collected throughout the exercise sessions and at three 10 minute intervals postexercise. Heart rate variability was evaluated for 10 minutes after each of two 30-minute recovery sessions, either resting or massage.
Results:
Heart rate returned to below resting levels (73 bpm) with 30 and 60 minutes of massage recovery (72 bpm and 63 bpm, respectively) compared to 30 and 60 minutes of resting recovery (77 bpm and 74 bpm, respectively). Heart rate variability data showed a more immediate shift to the parasympathetic state following 30 minutes of massage (1.152 LF/HF ratio) versus the 30-minute resting recovery (6.91 LF/HF ratio). It took 60 minutes of resting recovery to reach similar heart rate variability levels (1.216 LF/HF) found after 30 minutes of massage. Ventilations after 30 minutes of massage recovery averaged 7.1 bpm compared to 17.9 bpm after 30 minutes of resting recovery.
Conclusions:
No differences in EPOC were observed through either the resting or massage recovery based on the metabolic data collected. Massage was used to help the subject shift into parasympathetic activity more quickly than rest alone following a submaximal exercise session.
... As such, performing resistance exercise before endurance exercise may promote greater overall energy expenditure and potentially fat metabolism. However, others have demonstrated no order effect on oxygen consumption both during [88,89] and after concurrent sessions [90]. Rather than the training program per se, it is also possible the divergent group changes in fat mass may relate to changes in overall energy intake over the course of the training program. ...
Background
The importance of concurrent exercise order for improving endurance and resistance adaptations remains unclear, particularly when sessions are performed a few hours apart. We investigated the effects of concurrent training (in alternate orders, separated by ~3 hours) on endurance and resistance training adaptations, compared to resistance-only training.
Materials and methods
Twenty-nine healthy, moderately-active men (mean ± SD; age 24.5 ± 4.7 y; body mass 74.9 ± 10.8 kg; height 179.7 ± 6.5 cm) performed either resistance-only training (RT, n = 9), or same-day concurrent training whereby high-intensity interval training was performed either 3 hours before (HIIT+RT, n = 10) or after resistance training (RT+HIIT, n = 10), for 3 d.wk⁻¹ over 9 weeks. Training-induced changes in leg press 1-repetition maximal (1-RM) strength, countermovement jump (CMJ) performance, body composition, peak oxygen uptake (), aerobic power (), and lactate threshold () were assessed before, and after both 5 and 9 weeks of training.
Results
After 9 weeks, all training groups increased leg press 1-RM (~24–28%) and total lean mass (~3-4%), with no clear differences between groups. Both concurrent groups elicited similar small-to-moderate improvements in all markers of aerobic fitness ( ~8–9%; ~16-20%; ~14-15%). RT improved CMJ displacement (mean ± SD, 5.3 ± 6.3%), velocity (2.2 ± 2.7%), force (absolute: 10.1 ± 10.1%), and power (absolute: 9.8 ± 7.6%; relative: 6.0 ± 6.6%). HIIT+RT elicited comparable improvements in CMJ velocity only (2.2 ± 2.7%). Compared to RT, RT+HIIT attenuated CMJ displacement (mean difference ± 90%CI, -5.1 ± 4.3%), force (absolute: -8.2 ± 7.1%) and power (absolute: -6.0 ± 4.7%). Only RT+HIIT reduced absolute fat mass (mean ± SD, -11.0 ± 11.7%).
Conclusions
In moderately-active males, concurrent training, regardless of the exercise order, presents a viable strategy to improve lower-body maximal strength and total lean mass comparably to resistance-only training, whilst also improving indices of aerobic fitness. However, improvements in CMJ displacement, force, and power were attenuated when RT was performed before HIIT, and as such, exercise order may be an important consideration when designing training programs in which the goal is to improve lower-body power.
... Drummond, et al. and Villaca Alves, et al. demonstrated that in the post-exercise VO 2 was significantly greater when endurance exercise was performed before resistance exercise [20,21]. Against these results, Oliveira and Oliveira reported that the order of execution did not affect the Excess Post-Exercise Oxygen Consumption (EPOC) magnitude and duration [22]. In addition, Jones, et al. showed that blood cortisol and lactate concentrations were greater when endurance exercise was conducted prior to strength exercise [23]. ...
Purpose: The purpose of this study was the effect of concurrent
exercise order on lipid profile, leptin serum and insulin
resistance index in non-athlete overweight women.
Methods: Thirty female students (age = 23.2 ± 2.4 year, BMI
= 27.87 ± 1.3 kg/m2) volunteered to participate in this study
and were randomly divided into three groups of 10 people
taking the Concurrent Endurance-Resistance (CER), Concurrent
Resistance- Endurance (CRE) and Control (C). Two
exercise groups performed the same concurrent exercise,
but the order of endurance and resistance exercise were
different in two groups. Fasting blood samples were collected
before and after completion of the exercise. The paired
sample t-test was used to determine differences within a
group, and variation between groups analysis of variance
(ANOVA) and LSD were used.
Results: The implementation of a concurrent exercise session
in two exercise groups except for the indicators of HDL
that there was no significant change, caused to significantly
decreases in TC, TG, LDL, insulin, insulin resistance indices
and leptin serum that this rate of changes was significant
compared with the control group. But no significant
difference was observed between implementation of two
methods of concurrent exercise. In addition, the control
group did not change significantly in none of the variables.
Conclusion: Although the implementation one session of
a combination of resistance and endurance exercise improves
lipid profile, insulin resistance index and leptin serum
but the effectiveness of two methods of concurrent endurance-
resistance and resistance-endurance were similar.
... Di Blasio et al. [30] found the magnitude of EPOC to be similar in previously untrained women performing aerobic followed by strength training and vice versa. However, in physically active men both no differences [31,32] and a greater EPOC response following the exercise order commencing with aerobic exercise [33] were observed. The latter finding may at least in part be explained with a rather low endurance exercise intensity and volume (25 min at 70% of VO 2max ) in this study, in fact being comparable to an active recovery strategy and, thus, enhancing lactate removal [34]. ...
Performing aerobic and strength training in close proximity may compromise the recovery between subsequent training sessions and detrimentally affect chronic physiological adaptations and exercise performance. While during the past decade the number of studies focusing on the acute physiological effects of exercise sequencing (aerobic followed by strength exercise or vice versa) has increased, a thorough review of existing literature reveals that findings from these studies do not ultimately translate into long-term training. Moreover, much less is known on possibly specific adaptations to concurrent training performed within the same training session or split onto alternating days. This chapter will focus on the magnitude of adaptations in physiological function and performance in respect to different modes of combined training.
... . However, our results demonstrated no differences in the post-exercise VO 2 values when performing different intra-session sequences or using different aerobic modalities. In accordance with our findings, Oliveira & Oliveira[20] demonstrated that different intra-session exercise sequences during concurrent training do not affect the EPOC magnitude. The discrepancy between these results may be due to variations in study design such as exercises performed, total overload, recovery intervals, and energy assessment protocol[21].The American College of Sports Medicine suggests an EE equivalent of 1200 to 2000 kcal/week to prevent a weight gain greater than 3% in most adults[1]. ...
To compare the acute effects of different intra-session exercise sequences and aerobic exercise modalities during concurrent training sessions on oxygen consumption (VO2) and energy expenditure (EE) in young women. Eleven young women volunteered to participate in this study and underwent tests of their dynamic strength and a maximal incremental test on both the treadmill and cycle ergometer. Four concurrent training sessions were performed: resistance-running (RRu), resistance-cycling (RC), running-resistance (RuR) and cycling-resistance (CR). The aerobic exercise lasted 30 minutes and was performed at a heart rate equivalent to 95% of the second ventilatory threshold. The resistance exercise lasted approximately 21 minutes and consisted of 4 sets of 10 RM in each exercise. The VO2 was continuously evaluated through the portable gas analyser. No differences were found in the VO2 between the intra-session exercise sequence independently of aerobic modality (i.e., RRu vs. RuR, and RC vs. CR), and the sessions with the running aerobic exercise showed greater VO2 than sessions using cycling aerobic exercise in both exercise sequences (VO2aerobic (ml · kg⁻¹ · min⁻¹) – RRu: 27.5; RuR: 27.1; RC: 20.2; CR: 20.8). The present study showed that the intra-session exercise sequence during concurrent training does not influence VO2. However, the optimal combination of resistance and aerobic exercise should include running in order to increase VO2 and optimize EE.
... For pre-exercise VO 2 measurements, participants lay supine in a darkened room and were asked to remain quiet and still until VO 2 had stabilized and 10-15 min of stable VO 2 data had been collected using a breath-by-breath gas analysis system (Quark CPET, Cosmed, Rome, Italy). This method of obtaining a baseline measurement is similar to those reported elsewhere [19][20][21]. The gas analyzers and flow metre of the gas analysis system were calibrated shortly before the start of each trial according to the manufacturer's instructions. ...
The return towards resting homeostasis in the post-exercise period has the potential to represent the internal training load of the preceding exercise bout. However, the relative potential of metabolic and autonomic recovery measurements in this role has not previously been established. Therefore the aim of this study was to investigate which of 4 recovery measurements was most closely associated with Borg’s Rating of Perceived Exertion (RPE), a measurement widely acknowledged as an integrated measurement of the homeostatic stress of an exercise bout. A heterogeneous group of trained and untrained participants (n = 36) completed a bout of exercise on the treadmill (3 km at 70% of maximal oxygen uptake) followed by 1 hour of controlled recovery. Expired respiratory gases and heart rate (HR) were measured throughout the exercise and recovery phases of the trial with recovery measurements used to calculate the magnitude of excess post-exercise oxygen consumption (EPOCMAG), the time constant of the EPOC curve (EPOCτ), 1 min heart rate recovery (HRR60s) and the time constant of the HR recovery curve (HRRτ) for each participant. RPE taken in the last minute of exercise was significantly associated with HRR60s (r=-0.69), EPOCτ (r=0.52) and HRRτ (r=0.43) but not with EPOCMAG.This finding suggests that, of the 4 recovery measurements under investigation, HRR60s shows modest potential to represent inter-individual variation in the homeostatic stress of a standardized exercise bout, in a group with a range of fitness levels.
... However, the sequence of combining the two types of exercise may also be an important way to maximize benefits of the concurrent training to promote energy expenditure. However, the influence of the EE and RE sequence on volume of oxygen consumed per min (VO 2 ) is scarcely reported in the literature (Oliveira & Oliveira, 2011;Alves et al., 2012;Davitt et al., 2014). Alves et al. (2012) showed no significant differences between different combinations of EE and RE exercises, but found a higher VO 2 in the 5-to 15-min postexercise period when EE was performed before RE and in the 10-15 min when the EE was performed in the middle of RE blocks. ...
The combination of step choreography (SC) with resistance training exercises (RE) in the same session is common in class fitness rooms populated mainly by women to increase energy expenditure. The aim of this study was to evaluate the differences in the exercise oxygen uptake and postexercise between two different combinations of resistance training exercises and step choreography, regarding the order of execution. Thirteen active women (30±31 ` 4±42 years, 62±02 ` 5±37 kg, 162±65 ` 4±40 cm, 19±14 ` 3±29% body fat) performed two combinations: step choreography before resistance training, where resistance training was divided into two blocks of analysis (10 min each); and step chore- ography divided into three equal blocks (10 min for each block), before, in the middle and after resistance exercise. There were significant differences (P<0.05) between the two sessions in oxygen uptake postexercise in the period of 0–5 min. A significant increase (P<0.0001) in the oxygen uptake absolute and relative in the heart rate between blocks 1 and 2 of resistance exercise in the two sessions was observed. In the step choreography in blocks, a significant (P = 0.001) decrease between blocks 2 and 3 in the step choreography before resistance exercise and a significant (P<0.05) increase in the heart rate in both sessions between blocks were observed. The combination of step choreography and resistance exercises during the same exercise session is a good strategy to promote an elevation of women’s oxygen uptake during and after an exercise session, independent of the sequence used.
... It is hypothesized that metabolism is elevated due to protein turnover and tissue repair after resistance exercises 94,107,108) . Moreover, Oliveira and Oliveira 109) recently showed that EPOC is unaffected by the order of resistance and aerobic training. ...
Even a small daily positive energy balance leads to weight gain over a period of a few years. Understanding changes in the energy balance is important for preventing obesity. The purpose of this review is to discuss the variable factors involved in total daily energy expenditure (TDEE) in humans. TDEE comprises the resting metabolic rate (RMR), diet-induced thermogenesis (DIT), and physical activity energy expenditure (PAEE). RMR comprises the largest component (~60%) of TDEE. DIT accounts for approximately 10% of TDEE, and PAEE approximately 30%. A large part of the variation in RMR can be explained by body composition and body size. The primary determinant of DIT is meal size and composition. Body size and aging are also potential factors of variability in DIT. PAEE can be further categorized into exercise-induced energy expenditure (EXEE) and non-exercise activity thermogenesis (NEAT). EXEE mainly depends on body size, and exercise intensity and duration. In addition, excess post-exercise oxygen consumption following exercise is thought to have a significant impact on total EXEE. Based on a review of published studies, however, it is clear that in most individuals, EXEE is not a large contributor to TDEE. On the other hand, NEAT has the greatest impact on variation in TDEE, which varies by up to 2000 kcal per day between people of similar body size. In summary, there are several factors involved in the contribution of each component of TDEE. Although each factor contributes to small changes in TDEE, the sum of these influences may induce a large energy imbalance.
... The training sequence of endurance and resistance exercise, at least in theory, could influence acute physiological responses: indeed, while the sequence seems to have no effects on absolute or relative VO 2 , heart rate and RER during exercise; post-exercise VO 2 seems to be affected by the order of concurrent endurance and resistance exercise (Villaca Alves et al., 2011). Post-exercise VO 2 was significantly greater when endurance exercise was performed before resistance exercise in several (Drummond et al., 2005; Villaca Alves et al., 2011) but not all studies: Oliveira and Oliveira (2011) found that the order of execution did not affect the EPOC magnitude and duration. To the best of our knowledge, the literature is lacking in studies conducted on healthy but non-trained women that investigate the acute effects of all of the possible combinations of concurrent endurance and resistance training. ...
Physical exercise is used for the promotion and maintenance of
good health and for the improvement of physical fitness. Both
endurance and resistance exercises are needed to carry out a
complete training program. Because time may be a barrier to
physical exercise practice, the aim of this study was to verify
whether the order of execution of endurance and resistance
exercises, in concurrent training, has different effects on the
metabolic responses during recovery. Thirteen healthy women
[24.40 (1.67) years, Mean (SD)] were investigated for energy
expenditure (EE), oxygen consumption (VO2), ventilation (Ve),
respiratory frequency (RF), proportion of oxygen in expired air
(FeO2) and ratings of perceived exertion (RPE) both before and
after three concurrent endurance and resistance trainings, carried
out in different orders: endurance-resistance training (ERT),
resistance-endurance training (RET) and alternating enduranceresistance
training (AERT). AERT elicited a significantly
greater increase of EE, VO2, and Ve and a greater decrease of
FeO2. ERT elicited a lower increase of RPE. Acute post-exercise
physiological responses to concurrent endurance and resistance
physical exercise seem to depend on the order of execution of
the two parts: among the selected protocols, AERT seems to
elicit the best responses.
Thirty-five healthy men were matched and randomly assigned to one of four training groups that performed high-intensity strength and endurance training (C; n = 9), upper body only high-intensity strength and endurance training (UC; n = 9), high-intensity endurance training (E; n = 8), or high-intensity strength training (ST; n = 9). The C and ST groups significantly increased one-repetition maximum strength for all exercises (P < 0.05). Only the C, UC, and E groups demonstrated significant increases in treadmill maximal oxygen consumption. The ST group showed significant increases in power output. Hormonal responses to treadmill exercise demonstrated a differential response to the different training programs, indicating that the underlying physiological milieu differed with the training program. Significant changes in muscle fiber areas were as follows: types I, IIa, and IIc increased in the ST group; types I and IIc decreased in the E group; type IIa increased in the C group; and there were no changes in the UC group. Significant shifts in percentage from type IIb to type IIa were observed in all training groups, with the greatest shift in the groups in which resistance trained the thigh musculature. This investigation indicates that the combination of strength and endurance training results in an attenuation of the performance improvements and physiological adaptations typical of single-mode training.
Simultaneously training for both strength and endurance results in a compromised adaptation, compared with training for either exercise mode alone. This has been variously described as the concurrent training effect or the interference effect. It now appears that the genetic and molecular mechanisms of adaptation induced by resistance- and endurance-based training are distinct, with each mode of exercise activating and (or) repressing specific subsets of genes and cellular signalling pathways. This brief review will summarize our current understanding of the molecular responses to strength and endurance training, and will examine the molecular evidence for an interference effect when concurrent training is undertaken. A better understanding of the activation and interaction of the molecular pathways in response to these different modes of exercise will permit sport scientists to develop improved training programs capable of maximizing both strength and endurance.
A common belief among many clinicians and trainers is that intensive simultaneous training for muscle strength and cardiovascular endurance is counterproductive. To test this premise, 14 healthy, untrained men trained four days per week for 20 weeks on a bicycle ergometer for endurance (END Group, n = 4), on an isokinetic device for increased torque production (ITP Group, n = 5), or on both devices (COMBO Group, n = 5). The ITP and COMBO groups had equal torque gains throughout the study (234 +/- 45 and 232 +/- 23 N.m, respectively). After 11 weeks, both END and COMBO groups had similar gains in maximal oxygen consumption (VO2max) (in milliliters per kilogram of body weight per minute). During the last half of the study, however, the END Group had a significant gain in VO2max (p less than .05) of 4.7 +/- 1.2 mL.kg-1.min-1, whereas the COMBO Group had a nonsignificant gain (p greater than .05) of 1.8 +/- 0.6 mL.kg-1.min-1. In harmony with this finding, the END Group showed a significant increase (p less than .05) in citrate synthase activity (15.5 +/- 7.9 mumol.g-1.min-1), whereas the COMBO Group had no significant increase. The authors concluded that simultaneous training may inhibit the normal adaptation to either training program when performed alone. The extent of the interference probably depends on the nature and intensity of the individual training program. [Nelson AG, Arnall DA, Loy SF, et al: Consequences of combining strength and endurance training regimens.
This study was undertaken to determine the effect of exercise duration on the time course and magnitude of excess postexercise O2 consumption (EPOC). Six healthy male subjects exercised on separate days for 80, 40, and 20 min at 70% of maximal O2 consumption on a cycle ergometer. A control experiment without exercise was performed. O2 uptake, respiratory exchange ratio (R), and rectal temperature were monitored while the subjects rested in bed 24 h postexercise. An increase in O2 uptake lasting 12 h was observed for all exercise durations, but no increase was seen after 24 h. The magnitude of 12-h EPOC was proportional to exercise duration and equaled 14.4 +/- 1.2, 6.8 +/- 1.7, and 5.1 +/- 1.2% after 80, 40, and 20 min of exercise, respectively. On the average, 12-h EPOC equaled 15.2 +/- 2.0% of total exercise O2 consumption (EOC). There was no difference in EPOC:EOC for different exercise durations. A linear decrease with exercise duration was observed in R between 2 and 24 h postexercise. No change was observed in recovery rectal temperature. It is concluded that EPOC increases linearly with exercise duration at a work intensity of 70% of maximal O2 consumption.
The classical "oxygen debt" hypothesis formulated by Hill and associates in the 1920s was an attempt to link the metabolism of lactic acid with the O2 consumption in excess of resting that occurs after exercise. The O2 debt was hypothesized to represent the oxidation of a minor fraction (1/5) of the lactate formed during exercise, to provide the energy to reconvert the remainder (4/5) of the lactate to glycogen during recovery. In 1933 Margaria et al. modified this hypothesis by distinguishing between initial, fast ("alactacid"), and second, slow ("lactacid"), O2-debt curve components. They hypothesized that the fast phase of the post-exercise O2 consumption curve was due to the restoration of phosphagen (ATP + CP). It is now probable that the original lactic acid explanation of the O2 debt was too simplistic. Numerous studies on several species have provided evidence demonstrating a dissociation between the kinetics of lactate removal and the slow component of the post-exercise VO2. The metabolism of lactate, a readily oxidizable substrate, following exercise appears to be directed primarily toward energy production in mitochondria. The elevated concentration of lactate present at the end of exercise may be viewed as a "reservoir of carbon," which may serve as a source of oxidative ATP production or as a source of carbon skeletons for the synthesis of glucose, glycogen, amino acids, and TCA cycle intermediates. The metabolic basis of the elevated post-exercise VO2 may be understood in terms of those factors which directly or indirectly influence mitochondrial O2 consumption. Included among these factors are catecholamines, thyroxine, glucocorticoids, fatty acids, calcium ions, and temperature. Of these, elevated temperature is perhaps the most important. As no complete explanation of the post-exercise metabolism exists, it is recommended that the term "O2 debt" be used to describe a set of phenomena during recovery from exercise. The terms "alactacid debt" and "lactacid debt," which suggest a mechanism, are inappropriate. Use of alternative terms, e.g., "excess post-exercise oxygen consumption" (EPOC) and "recovery O2," will avoid implication of causality in describing the elevation in metabolic rate above resting levels after exercise.
There is a paucity of research concerning energy expenditure during and after circuit weight training (CWT). There is evidence that duration of rest between sets affects metabolic responses to resistive exercise. The purpose of the study was to determine the effect of rest-interval duration upon the magnitude of 1 h of excess postexercise oxygen consumption (EPOC).
Seven healthy men completed two randomized circuit weight training sessions using 20-s and 60-s rest intervals (20 RI, 60 RI). Sessions included two circuits of eight upper and lower body resistive exercises in which 20 repetitions were performed at 75% of a previously determined 20 repetition maximum.
The 1 h EPOC of 10.3 +/- 0.57 L for the 20 RI session was significantly higher than 7.40 +/- 0.39 L for the 60 RI session. The net caloric expenditure during 1 h of recovery from the 20 RI session was significantly higher than that of the 60 RI session (51.51 +/- 2.84 vs 37.00 +/- 1.97 kcal); however, total gross energy expenditure (exercise + 1 h recovery) was significantly greater for the 60 RI protocol (277.23 kcal) than the 20 RI protocol (242.21 kcal).
Data demonstrate that shortening the rest interval duration will increase the magnitude of 1 h EPOC from CWT; however, the exercise + recovery caloric costs from CWT are slightly greater for a longer rest interval duration protocol. These data suggest that total caloric cost be taken into account for CWT.
In the recovery period after exercise there is an increase in oxygen uptake termed the ‘excess post-exercise oxygen consumption’ (EPOC), consisting of a rapid and a prolonged component. While some studies have shown that EPOC may last for several hours after exercise, others have concluded that EPOC is transient and minimal. The conflicting results may be resolved if differences in exercise intensity and duration are considered, since this may affect the metabolic processes underlying EPOC. Accordingly, the absence of a sustained EPOC after exercise seems to be a consistent finding in studies with low exercise intensity and/or duration. The magnitude of EPOC after aerobic exercise clearly depends on both the duration and intensity of exercise. A curvilinear relationship between the magnitude of EPOC and the intensity of the exercise bout has been found, whereas the relationship between exercise duration and EPOC magnitude appears to be more linear, especially at higher intensities.
Differences in exercise mode may potentially contribute to the discrepant findings of EPOC magnitude and duration. Studies with sufficient exercise challenges are needed to determine whether various aerobic exercise modes affect EPOC differently. The relationships between the intensity and duration of resistance exercise and the magnitude and duration of EPOC have not been determined, but a more prolonged and substantial EPOC has been found after hardversus moderate-resistance exercise. Thus, the intensity of resistance exercise seems to be of importance for EPOC.
Lastly, training status and sex may also potentially influence EPOC magnitude, but this may be problematic to determine. Still, it appears that trained individuals have a more rapid return of post-exercise metabolism to resting levels after exercising at either the same relative or absolute work rate; however, studies after more strenuous exercise bouts are needed. It is not determined if there is a sex effect on EPOC.
Finally, while some of the mechanisms underlying the more rapid EPOC are well known (replenishment of oxygen stores, adenosine triphosphate/creatine phosphate resynthesis, lactate removal, and increased body temperature, circulation and ventilation), less is known about the mechanisms underlying the prolonged EPOC component. A sustained increased circulation, ventilation and body temperature may contribute, but the cost of this is low. An increased rate of triglyceride/fatty acid cycling and a shift from carbohydrate to fat as substrate source are of importance for the prolonged EPOC component after exhaustive aerobic exercise. Little is known about the mechanisms underlying EPOC after resistance exercise.
Seventeen women were divided into lean (19.5 +/- 0.5 years; 22.2 +/- 0.6 kg.m(-2)) and obese (20.4 +/- 0.5 years; 34.9 +/- 2.1 kg.m(-2)) groups. On completion of a submax cycle ergometer test and 10-repetition maximum (10RM) of 5 exercises on a Smith machine, subjects returned for 2 exercise sessions during menses. Session 1 consisted of performing 3 sets of 10 repetitions at 70% of the predetermined 10RM for the following exercises: squat, calf raises, bench press, upright row, and shoulder press. Session 2 consisted of cycling at 60-65% VO2max for a duration that would expend the same number of calories as the resistance session. Postexercise respiratory exchange ratio and EPOC magnitude/duration were similar for both groups. These findings indicate that women who are lean or obese will respond similarly to exercise at similar relative intensities and that aerobic and resistance exercise of equal caloric expenditure will elicit similar EPOC responses.
We examined acute molecular responses in skeletal muscle to divergent exercise stimuli by combining consecutive bouts of resistance and endurance exercise. Eight men [22.9 +/- 6.3 yr, body mass of 73.2 +/- 4.5 kg, peak O(2) uptake (Vo(2peak)) of 54.0 +/- 5.7 ml.kg(-1) x min(-1)] were randomly assigned to complete trials consisting of either resistance exercise (8 x 5 leg extension, 80% 1 repetition maximum) followed by a bout of endurance exercise (30 min cycling, 70% Vo(2peak)) or vice versa. Muscle biopsies were obtained from the vastus lateralis at rest, 15 min after each exercise bout, and after 3 h of passive recovery to determine early signaling and mRNA responses. Phosphorylation of Akt and Akt1(Ser473) were elevated 15 min after resistance exercise compared with cycling, with the greatest increase observed when resistance exercise followed cycling ( approximately 55%; P < 0.01). TSC2-mTOR-S6 kinase phosphorylation 15 min after each bout of exercise was similar regardless of the exercise mode. The cumulative effect of combined exercise resulted in disparate mRNA responses. IGF-I mRNA content was reduced when cycling preceded resistance exercise (-42%), whereas muscle ring finger mRNA was elevated when cycling was undertaken after resistance exercise ( approximately 52%; P < 0.05). The hexokinase II mRNA level was higher after resistance cycling ( approximately 45%; P < 0.05) than after cycling-resistance exercise, whereas modest increases in peroxisome proliferator-activated receptor gamma coactivator-1alpha mRNA did not reveal an order effect. We conclude that acute responses to diverse bouts of contractile activity are modified by the exercise order. Moreover, undertaking divergent exercise in close proximity influences the acute molecular profile and likely exacerbates acute "interference."
Twenty specialist marathon runners and 23 specialist ultra-marathon runners underwent maximal exercise testing to determine the relative value of maximum oxygen consumption (VO2max), peak treadmill running velocity, running velocity at the lactate turnpoint, VO2 at 16 km h-1, % VO2max at 16 km h-1, and running time in other races, for predicting performance in races of 10-90 km. Race time at 10 or 21.1 km was the best predictor of performance at 42.2 km in specialist marathon runners and at 42.2 and 90 km in specialist ultra-marathon runners (r = 0.91-0.97). Peak treadmill running velocity was the best laboratory-measured predictor of performance (r = -0.88(-)-0.94) at all distances in ultra-marathon specialists and at all distances except 42.2 km in marathon specialists. Other predictive variables were running velocity at the lactate turnpoint (r = -0.80(-)-0.92); % VO2max at 16 km h-1 (r = 0.76-0.90) and VO2max (r = 0.55(-)-0.86). Peak blood lactate concentrations (r = 0.68-0.71) and VO2 at 16 km h-1 (r = 0.10-0.61) were less good predictors. These data indicate: (i) that in groups of trained long distance runners, the physiological factors that determine success in races of 10-90 km are the same; thus there may not be variables that predict success uniquely in either 10 km, marathon or ultra-marathon runners, and (ii) that peak treadmill running velocity is at least as good a predictor of running performance as is the lactate turnpoint. Factors that determine the peak treadmill running velocity are not known but are not likely to be related to maximum rates of muscle oxygen utilization.
Data are reported on the net recovery O2 consumption (VO2) for nine male subjects (mean age 21.9 yr, VO2max 63.0 ml.kg-1.min-1, body fat 10.6%) used in a 3 (independent variables: intensities of 30, 50, and 70% VO2max) x 3 (independent variables: durations of 20, 50, and 80 min) repeated measures design (P less than or equal to 0.05). The 8-h mean excess postexercise O2 consumptions (EPOCs) for the 20-, 50-, and 80-min bouts, respectively, were 1.01, 1.43, and 1.04 liters at 30% VO2max (6.8 km/h); 3.14, 5.19, and 6.10 liters at 50% VO2max (9.5 km/h); and 5.68, 10.04, and 14.59 liters at 70% VO2max (13.4 km/h). The mean net total O2 costs (NTOC = net exercise VO2 + EPOC) for the 20-, 50-, and 80-min bouts, respectively, were 20.48, 53.20, and 84.23 liters at 30% VO2max; 38.95, 100.46, and 160.59 liters at 50% VO2max; and 58.30, 147.48, and 237.17 liters at 70% VO2max. The nine EPOCs ranged only from 1.0 to 8.9% of the NTOC (mean 4.8%) of the exercise. These data, therefore, indicate that in well-trained subjects the 8-h EPOC per se comprises a very small percentage of the NTOC of exercise.
The purpose of this study was to examine 1) the effect of two exercise intensities of equal caloric output on the magnitude (kcal) and duration of excess postexercise oxygen consumption (EPOC) and 2) the effect of exercise of equal intensity but varying duration on EPOC. Ten trained male triathletes performed three cycle ergometer exercises: high intensity-short duration (HS), low intensity-short duration (LS), and low intensity-long duration (LL). Baseline VO2 was measured for 1 h prior to each exercise condition. Postexercise VO2 was measured continuously until baseline VO2 was achieved. The duration of EPOC was similar for HS (33 +/- 10 min) and LL (28 +/- 14 min), and both were significantly longer (P less than 0.05) than the EPOC following LS (20 +/- 5 min). However, total net caloric expenditure was significantly more (P less than 0.05) for HS (29 +/- 8 kcal) than for either LS (14 +/- 6 kcal) or LL (12 +/- 7 kcal). The exercise conditions used in this study did not produce a prolonged EPOC. However, the exercise intensity was shown to affect both the magnitude and duration of EPOC, whereas the exercise duration affected only the duration of EPOC. Moreover, the duration of EPOC and the subsequent caloric expenditure were not necessarily related. Based on the resulting magnitude of the postexercise energy expenditure, it is possible that EPOC may be of some value for weight control over the long term.
Variations in heart rate during exercise correlate with changes of exercise intensity and may be measured directly by radiotelemetry and continuous ECG recording. The heart rate can also be recorded in the memory of a microcomputer, which can be carried on the wrist as easily as a watch. The device has a transmitter and a receiver. By recording the heart rate during a training session or a segment of training, and calculating the average of the heart rate and comparing this average to both the maximum heart rate of the individual and his heart rate at rest, the relative heart rate to the intensity of the work load (% maximum heart rate) can be calculated. These results are useful in planning optimal training intensities for both the healthy and rehabilitating athlete. The use of target heart rate as a tool for exercise prescription is common. It represents the percentage difference between resting and maximum heart rate added to the resting heart rate. For calculating target heart rate there are also 2 other methods. The first represents the percentage of the maximum heart rate (%HRmax) calculated from zero to peak heart rate. The second represents the heart rate at a specified percentage of maximum MET (VO2max). An appropriate individual heart rate for each level of an endurance performance is best determined in the laboratory. This is carried out by increasing the speed of the runner in stages on a treadmill and by measuring the oxygen uptake, the lactic acid concentration in the blood and corresponding variations in the heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)
Postexercise energy metabolism was examined in male subjects age 22-35 years in response to three different treatments: a strenuous bout of resistive exercise (REx), a bout of stationary cycling (AEx) at 50% peak VO2, and a control condition (C) of quiet sitting. Resting metabolic rate (RMR) was measured the morning of and the morning following each condition. Recovery oxygen consumption (RcO2) was measured for 5 hr following each treatment. Total 5-hr RcO2 was higher for the REx treatment relative to both AEx and C, with the largest treatment differences occurring early during recovery. There were no large treatment differences in postexercise respiratory exchange ratio values, except for the first hour of recovery following REx. RMR measured 14.5 hr postexercise for the REx condition was significantly elevated compared to C. These results suggest that strenuous resistive exercise results in a greater excess postexercise oxygen consumption compared to steady-state endurance exercise of similar estimated energy cost.
Historically, the achievement of maximal oxygen uptake (VO2max) has been based on objective criteria such as a leveling off of oxygen uptake with an increase in work rate, high levels of lactic acid in the blood in the minutes following the exercise test, elevated respiratory exchange ratio, and achievement of some percentage of an age-adjusted estimate of maximal heart rate. These criteria are reviewed relative to their history, the degree to which they have been achieved in published research, and how investigators and reviewers follow them in current practice. The majority of the criteria were based on discontinuous protocols, often carried out over several days. Questions are raised about the applicability of these criteria to modern continuous graded exercise test protocols, and our lack of consistency in the terminology we use relative to the measurement of maximal oxygen uptake.
The purpose of this study was to compare the magnitude and duration of excess post-exercise O2 consumption (EPOC) measured after submaximal cycling at three different intensities of equivalent energy cost but all performed below the anaerobic threshold (AT). Eight healthy young women performed the three cycling sessions after an initial determination of VO2max (M +/- SD) (41.8 +/- 7.0 ml.kg-1.min-1) and AT (73 +/- 5% VO2max). The high intensity (HI) exercise was performed at 65% VO2max (90% of AT workload) for 30 minutes, while the moderate (MI) and low intensity (LI) exercise sessions were performed at approximately 55% VO2max (75% AT) and -45% VO2max (60% AT) respectively, until the energy cost matched that expended in the HI condition. Prior to each exercise session baseline resting VO2 and respiratory exchange ratio (RER) were measured by open circuit spirometry at the end of a 35 min period of supine rest. These measures were also made during the exercise and recovery periods. Post-exercise VO2 was measured continuously until baseline VO2 (within 1 SD of resting value for 2 consecutive min) was reached. The duration of EPOC (13-14 min) was similar following all three exercise sessions. The gross EPOC energy expenditure and VO2 were both significantly greater (p < 0.01) following the HI (137.0 +/- 6.3 kJ and 6.63 +/- 0.30 1) condition than the MI condition (116.6 +/- 8.7 kJ and 5.69 +/- 0.42 1) but no significant differences existed between the MI and LI (107.4 +/- 5.8 kJ and 5.24 +/- 0.29 1) conditions for either of these variables. It was concluded that the magnitude of EPOC following submaximal exercise of equivalent energy cost but below the AT, is determined more by the intensity of exercise rather that the exercise energy cost.
Although exercise intensity has been identified as a major determinant of the excess postexercise oxygen consumption (EPOC), no studies have compared the EPOC after submaximal continuous running and supramaximal interval running. Eight male middle-distance runners [age = 2.1 +/- 3.1 (SD) yr; mass = 67.8 +/- 5.1 kg; maximal oxygen consumption (VO2max) = 69.2 +/- 4.0 ml.kg-1.min-1] therefore completed two equated treatments of treadmill running (continuous running: 30 min at 70% VO2max; interval running: 20 x 1-min intervals at 105% VO2max with intervening 2-min rest periods) and a control session (no exercise) in a counter-balanced research design. The 9-h EPOC values were 6.9 +/- 3.8 and 15.0 +/- 3.3 liters (t-test:P = 0.001) for the submaximal and supramaximal treatments, respectively. These values represent 7.1 and 13.8% of the net total oxygen cost of both treatments. Notwithstanding the higher EPOC for supramaximal interval running compared with submaximal continuous running, the major contribution of both to weight loss is therefore via the energy expended during the actual exercise.
Increased fat oxidation during the recovery period from exercise is thought to be a contributing factor for excess postexercise oxygen consumption (EPOC). In an attempt to study the effect of serum free fatty acid (FFA) availability during exercise and recovery on the EPOC, nicotinic acid, a potent inhibitor of FFA mobilization from adipose tissue, was administered to five trained male cyclists prior to, during, and after a bout of cycling at 65% VO2max. In the nicotinic acid trial, a 500 mg dose of nicotinic acid was ingested prior to exercise, and 100 mg doses were ingested at 15, 30, and 45 min exercise, and 30 min recovery. The cyclists also completed a trial under control conditions. Serum FFA, serum glycerol, RER and VO2 were monitored during rest, exercise, and recovery, each of which was 1-h in duration. Nicotinic acid ingestion prevented the increase in serum FFA that occurred during exercise in the control trial. FFA levels during the nicotinic acid trial were significantly lower than control values during both exercise and recovery. Serum glycerol levels were also significantly lower during exercise in the nicotinic acid trial, indicative of a reduction in lipolysis. RER was not significantly different at rest or during exercise; however, RER values were significantly lower during recovery in the control trial, indicative of greater fat oxidation. For both treatments, postexercise VO2 remained elevated above resting levels at the completion of the 1-h recovery period. However, the magnitude of EPOC was significantly reduced after FFA blockade with nicotinic acid (3.4 +/- 0.61 vs 5.5 +/- 0.71). These results support the hypothesis that increased FFA metabolism during exercise and recovery is an important contributing factor to the magnitude of EPOC.
The purpose of this study was to determine whether aerobic fitness level would influence measurements of excess postexercise oxygen consumption (EPOC) and initial rate of recovery. Twelve trained [Tr; peak oxygen consumption (VO2 peak) = 53.3 +/- 6.4 ml . kg-1 . min-1] and ten untrained (UT; VO2 peak = 37.4 +/- 3.2 ml . kg-1 . min-1) subjects completed two 30-min cycle ergometer tests on separate days in the morning, after a 12-h fast and an abstinence from vigorous activity of 24 h. Baseline metabolic rate was established during the last 10 min of a 30-min seated preexercise rest period. Exercise workloads were manipulated so that they elicited the same relative, 70% VO2 peak (W70%), or the same absolute, 1.5 l/min oxygen uptake (VO2) (W1.5), intensity for all subjects, respectively. Recovery VO2, heart rate (HR), and respiratory exchange ratio (RER) were monitored in a seated position until baseline VO2 was reestablished. Under both exercise conditions, Tr had shorter EPOC duration (W70% = 40 +/- 15 min, W1.5 = 21 +/- 9 min) than UT (W70% = 50 +/- 14 min; W1.5 = 39 +/- 14 min), but EPOC magnitude (Tr: W70% = 3.2 +/- 1.0 liters O2, W1.5 = 1.5 +/- 0.6 liters O2; UT: W70% = 3.5 +/- 0.9 liters O2, W1.5 = 2.4 +/- 0.6 liters O2) was not different between groups. The similarity of Tr and UT EPOC accumulation in the W70% trial is attributed to the parallel decline in absolute VO2 during most of the initial recovery period. Tr subjects had faster relative decline during the fast-recovery phase, however, when a correction for their higher exercise VO2 was taken. Postexercise VO2 was lower for Tr group for nearly all of the W1.5 trial and particularly during the fast phase. Recovery HR kinetics were remarkably similar for both groups in W70%, but recovery was faster for Tr during W1.5. RER values were at or below baseline throughout much of the recovery period in both groups, with UT experiencing larger changes than Tr in both trials. These findings indicate that Tr individuals have faster regulation of postexercise metabolism when exercising at either the same relative or same absolute work rate.
Effect of weight training exercise and treadmill exercise on postexercise oxygen consumption. Med. Sci. Sports Exerc., Vol. 30, No. 4, pp. 518-522, 1998. To compare the effect of weight training (WT) and treadmill (TM) exercise on postexercise oxygen consumption (VO2), 15 males (mean +/- SD) age = 22.7 +/- 1.6 yr; height = 175.0 +/- 6.2 cm; mass = 82.0 +/- 14.3 kg) performed a 27-min bout of WT and a 27-min bout of TM exercise at matched rates of VO2. WT consisted of performing two circuits of eight exercises at 60% of each subject's one repetition maximum with a work/rest ratio of 45 s/60 s. Approximately 5 d after WT each subject walked or jogged on the TM at a pace that elicited an average VO2 matched with his mean value during WT. VO2 was measured continuously during exercise and the first 30 min into recovery and at 60 and 90 min into recovery. VO2 during WT (1.58 L.min-1) and TM exercise (1.55 L.min-1) were not significantly (P > 0.05) different; thus the two activities were matched for VO2. Total oxygen consumption during the first 30 min of recovery was significantly higher (P < 0.05) as a result of WT (19.0 L) compared with that during TM exercise (12.7 L). However, VO2 values at 60 (0.32 vs 0.29 L.min-1), and 90 min (0.33 vs 0.30 L.min-1) were not significantly different (P > 0.05) between WT and TM exercise, respectively. The results suggest that, during the first 30 min following exercise. WT elicits a greater elevated postexercise VO2 than TM exercise when the two activities are performed at matched VO2 and equal durations. Therefore, total energy expenditure as a consequence of WT will be underestimated if based on exercise VO2 only.
The purpose of this study was to characterize the effects of prolonged beta-adrenoceptor stimulation on O2 uptake and triglyceride/fatty acid (TG/FA) cycling during rest with and without previous exercise. Eight men performed two exercise (90 min cycling at 56 +/- 3 (SD)% of maximal O2 uptake, followed by 4.5 h bed rest) and two rest-control experiments. In one rest and one exercise experiment a bolus dose (5 micrograms) of the beta-adrenoceptor agonist isoprenaline was given immediately after exercise, followed by a continuous infusion (20 ng kg-1 min-1), and at the corresponding time in the rest experiment. In the other experiments saline was given instead. The O2 uptake increased in the post-exercise period both with and without beta-stimulation. The total excess post-exercise oxygen consumption (EPOC) was not different between saline (8.1 +/- 1.8 (SE) L) and isoprenaline administration (10.8 +/- 1.8 L, P = 0.40). Also, the total accumulated increase in O2 uptake for the 4.5 h period after isoprenaline infusion was not different between the rest (12.5 +/- 2.0 L) and the exercise experiments (15.2 +/- 1.7 L, P = 0.40). The rate of TG/FA cycling increased after both exercise and isoprenaline treatment, but no interaction effect was found. In conclusion, the increases observed in O2 uptake and the rate of TG/FA cycling during beta-adrenoceptor stimulation were not increased by a previous exercise bout.
Concurrent strength and endurance training appears to inhibit strength development when compared with strength training alone. Our understanding of the nature of this inhibition and the mechanisms responsible for it is limited at present. This is due to the difficulties associated with comparing results of studies which differ markedly in a number of design factors, including the mode, frequency, duration and intensity of training, training history of participants, scheduling of training sessions and dependent variable selection. Despite these difficulties, both chronic and acute hypotheses have been proposed to explain the phenomenon of strength inhibition during concurrent training. The chronic hypothesis contends that skeletal muscle cannot adapt metabolically or morphologically to both strength and endurance training simultaneously. This is because many adaptations at the muscle level observed in response to strength training are different from those observed after endurance training. The observation that changes in muscle fibre type and size after concurrent training are different from those observed after strength training provide some support for the chronic hypothesis. The acute hypothesis contends that residual fatigue from the endurance component of concurrent training compromises the ability to develop tension during the strength element of concurrent training. It is proposed that repeated acute reductions in the quality of strength training sessions then lead to a reduction in strength development over time. Peripheral fatigue factors such as muscle damage and glycogen depletion have been implicated as possible fatigue mechanisms associated with the acute hypothesis. Further systematic research is necessary to quantify the inhibitory effects of concurrent training on strength development and to identify different training approaches that may overcome any negative effects of concurrent training.
This study determined the effect of an intense bout of resistive exercise on postexercise oxygen consumption, resting metabolic rate, and resting fat oxidation in young women (N=7, ages 22-35). On the morning of Day 1, resting metabolic rate (RMR) was measured by indirect calorimetry. At 13:00 hr, preexercise resting oxygen consumption was measured followed by 100 min of resistive exercise. Postexercise oxygen consumption was then measured for a 3-hr recovery period. On the following morning (Day 2), RMR was once again measured in a fasted state at 07:00. Postexercise oxygen consumption remained elevated during the entire 3-hr postexercise recovery period compared to the pre-exercise baseline. Resting metabolic rate was increased by 4.2% (p<.05) from Day 1 (morning prior to exercise: 1,419 +/- 58 kcal/24hr) compared to Day 2 (16 hr following exercise: 1,479 +/- kcal/24hr). Resting fat oxidation as determined by the respiratory exchange ratio was also significantly elevated on Day 2 compared to Day 1. These results indicate that among young women, acute strenuous resistance exercise of the nature used in this study is capable of producing modest but prolonged elevations of postexercise metabolic rate and possibly fat oxidation.
This study investigated the acute effects of 45 min of resistance exercise (RE) on excess postexercise oxygen consumption (EPOC) and substrate oxidation 120 min after exercise in moderately trained women.
Ten RE trained women (age = 29 +/- 3 yr; ht = 168 +/- 8.3 cm; wt = 59 +/- 5.7 kg; VO2max = 38.3 +/- 4.7 mL.kg-1.min-1) underwent two trials: control sitting and RE. Subjects acted as their own controls in a random counterbalanced design. A 2-d nonexercise period was established between testing trials. Oxygen consumption (VO2) and respiratory exchange ratio (RER) were measured continuously by indirect calorimetry before, during, and after exercise and on a separate control day. RE consisted of 3 sets of 10 exercises at 10-repetition maximum with a 1-min rest period between each set. Fingertip samples of blood lactate concentration [BL] were collected immediately postexercise and every 30 min thereafter until [BL] returned to resting baseline values after exercise.
The overall 2-h EPOC was 6.2-L (RE = 33.4 +/- 5.1 L vs control = 27.2 +/- 0.3 L), corresponding to an 18.6% elevation over the control period. RER was significantly (P < 0.01) below the control RER from minute 30 to minute 120 postexercise (RE = 0.75 +/- 0.01 vs control = 0.85 +/- 0.01). During the last 30 min of recovery, VO2 and [BL] had returned to control/baseline values and fat oxidation was significantly (P < 0.0001) higher (29.2 vs 16.3 kcal) after RE compared with the control trial.
These data indicate that in young RE trained women, acute RE produces a modest increase in VO2 during a 2-h recovery period and an increase in fat oxidation.
To define and describe the essential terminology associated with dose-response issues in physical activity and health.
Recent consensus documents, position stands, and reports were used to provide reference definitions and methods of classifying physical activity and exercise.
The two principal categories of physical activity are occupational physical activity (OPA) and leisure-time physical activity (LTPA). OPA is usually referenced to an 8-h d, whereas the duration of LTPA is quite variable. LTPA includes all forms of aerobic activities, structured endurance exercise programs, resistance-training programs, and sports. Energy expenditure associated with aerobic activity can be expressed in absolute terms (kJ x min(-1)), referenced to body mass (METs), or relative to some maximal physiological response (i.e., maximal heart rate (HR) or aerobic power (VO(2max))). The net cost of physical activity should be used to express energy expenditure relative to dose-response issues. The intensity of resistance training is presented in terms relative to the greatest weight that can be lifted one time in good form (1RM). The intensity of OPA followed the guidance of a previous consensus conference. The intensity of most LTPA can be categorized using the standard aerobic exercise classifications; however, for long-duration (2+ hours) LTPA, the classifications for OPA may be more appropriate.
Physical activities should be classified in a consistent and standardized manner in terms of both energy expenditure and the relative effort required.
Increasing evidence suggests that the myogenic regulatory factors (MRFs) and IGF-I have important roles in the hypertrophy response observed after mechanical loading. We, therefore, hypothesized that a bout of heavy-resistance training would affect the MRF and IGF-I mRNA levels in human skeletal muscle. Six male subjects completed four sets of 6-12 repetitions on a leg press and knee extensor machine separated by 3 min. Myogenin, MRF4, MyoD, IGF-IEabc (isoforms a, b, and c) and IGF-IEbc (isoform b and c) mRNA levels were determined in the vastus lateralis muscle by RT-PCR before exercise, immediately after, and 1, 2, 6, 24, and 48 h postexercise. Myogenin, MyoD, and MRF4 mRNA levels were elevated (P < 0.005) by 100-400% 0-24 h postexercise. IGF-IEabc mRNA content decreased (P < 0.005) by approximately 44% after 1 and 6 h of recovery. The IGF-IEbc mRNA level was unaffected. The present study shows that myogenin, MyoD, and MRF4 mRNA levels are transiently elevated in human skeletal muscle after a single bout of heavy-resistance training, supporting the idea that the MRFs may be involved in regulating hypertrophy and/or fiber-type transitions. The results also suggest that IGF-IEa expression may be downregulated at the mRNA level during the initial part of recovery from resistance exercise.
The purpose of this study was to assess the validity and reliability of a Cosmed K4b2 portable telemetric gas analysis system. Twelve physically fit males performed a treadmill running session consisting of an easy 10 min run, a hard 3 min run and a 1 min sprint (with rest periods of 10 min separating each run), on four separate occasions. Sessions were identical with the exception of the apparatus used to measure VO2. During two (test-retest) sessions a Cosmed K4b2 portable gas analysis system was used; in another, a laboratory metabolic cart and, in one session, both systems were used to measure VO2 simultaneously. Comparison of Cosmed K4b2 and metabolic cart measurements in isolation revealed significantly (p < 0.05) increased values of VO2, VCO2, FE CO2 (except FE CO2 at 10 min) and lower values of FE O2 for each run duration by the Cosmed system. Linear regression equations to predict metabolic cart results from Cosmed values were, respectively; cart VO2 = 0.926 (Cosmed VO2-0.227 (r2 = 0.84) and cart VCO2 = 1.057 (Cosmed VCO2-0.606 (r2 = 0.92). Bland-Altman plots and comparison of the test-retest cosmed measurements revealed that the K4b2 system showed good repeatability of measurement for measures of VE, VO2 and VCO2, particularly for 10 min and 3 min tests (ICC = 0.7-0.9, p < 0.05). In conclusion, the Cosmed K4b2 portable gas analysis system recorded consistently higher VO2 and VCO2 measurements in comparison to a metabolic cart. However, satisfactory test-retest reliability of the system was demonstrated.
Excess postexercise oxygen consumption (EPOC) may describe the impact of previous exercise on energy metabolism. Ten males completed Resistance Only, Run Only, Resistance-Run, and Run-Resistance experimental conditions. Resistance exercise consisted of 7 lifts. Running consisted of 25 minutes of treadmill exercise. Vo(2) was determined during treadmill exercise and after each exercise treatment. Our findings indicated that treadmill exercise Vo(2) was significantly higher for Resistance-Run compared with Run-Resistance and Resistance Only at all time intervals. At 10 minutes postexercise, Vo(2) was greater for Resistance Only and Run-Resistance than for Resistance-Run. At 20 and 30 minutes, Vo(2) following Resistance Only was significantly greater than following Run Only. In conclusion, EPOC is greatest following Run-Resistance; however, treadmill exercise is more physiologically difficult following resistance exercise. Furthermore, the sequence of resistance and treadmill exercise influences EPOC, primarily because of the effects of resistance exercise rather than the exercise combination. We recommend performing aerobic exercise before resistance exercise when combining them into 1 exercise session.
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.
The purpose of this study was to investigate excess post-exercise oxygen consumption (EPOC) following a continuous 30 min bout of upper-body exercise (UBE) compared with 3 consecutive 10 min bouts of UBE. Ten male subjects (age (mean +/- standard deviation), 25.7 +/- 5.83 years; arm VO(2) (peak), 2.2 +/- 0.25 L x min(-1), on separate days (48 h between trials) and in counterbalanced order, performed a continuous 30 min bout of arm exercise at 60% of arm VO2 peak and 3 separate 10 min bouts of arm exercise at 60% of arm VO(2) (peak). Subjects reported to the laboratory rested and after a 12 h fast. Each test was preceded by a 30 min baseline test to determine resting metabolic rate. Post-exercise VO2 was continuously monitored until baseline was re-established. Results showed that the combined magnitude of the EPOCs from the intermittent exercise sessions was significantly (p > .05) greater (4.47 +/- 1.58 L O2) than that elicited from the continuous exercise session (1.54 +/- 1.25 L O2). These data indicate that separating a continuous 30 min arm exercise into 3 equal 10 min arm exercises will elicit a small but significantly higher EPOC, and thus result in greater post-exercise energy expenditure. This could be beneficial for those unable to perform lower-body exercise (LBE), or for those with limited exercise capacities.
Recovery from a bout of exercise is associated with an elevation in metabolism referred to as the excess post-exercise oxygen consumption (EPOC). A number of investigators in the first half of the last century reported prolonged EPOC durations and that the EPOC was a major component of the thermic effect of activity. It was therefore thought that the EPOC was a major contributor to total daily energy expenditure and hence the maintenance of body mass. Investigations conducted over the last two or three decades have improved the experimental protocols used in the pioneering studies and therefore have more accurately characterized the EPOC. Evidence has accumulated to suggest an exponential relationship between exercise intensity and the magnitude of the EPOC for specific exercise durations. Furthermore, work at exercise intensities >or=50-60% VO2max stimulate a linear increase in EPOC as exercise duration increases. The existence of these relationships with resistance exercise at this stage remains unclear because of the limited number of studies and problems with quantification of work intensity for this type of exercise. Although the more recent studies do not support the extended EPOC durations reported by some of the pioneering investigators, it is now apparent that a prolonged EPOC (3-24 h) may result from an appropriate exercise stimulus (submaximal: >or=50 min at >or=70% VO2max; supramaximal: >or=6 min at >or=105% VO2max). However, even those studies incorporating exercise stimuli resulting in prolonged EPOC durations have identified that the EPOC comprises only 6-15% of the net total oxygen cost of the exercise. But this figure may need to be increased when studies utilizing intermittent work bouts are designed to allow the determination of rest interval EPOCs, which should logically contribute to the EPOC determined following the cessation of the last work bout. Notwithstanding the aforementioned, the earlier research optimism regarding an important role for the EPOC in weight loss is generally unfounded. This is further reinforced by acknowledging that the exercise stimuli required to promote a prolonged EPOC are unlikely to be tolerated by non-athletic individuals. The role of exercise in the maintenance of body mass is therefore predominantly mediated via the cumulative effect of the energy expenditure during the actual exercise.
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31. Psilander, N, Damsgaard, R, and Pilegaard, H. Resistance exercise
alters MRF and IGF-I mRNA content in human skeletal muscle.