Recovery Energy Expenditure Research Articles

COMPARISON OF EPOC AND RECOVERY ENERGY EXPENDITURE BETWEEN HIIT AND CONTINUOUS AEROBIC EXERCISE TRAINING

ABSTRACT Objectives: The objective of this study was to compare EPOC - excess post-exercise oxygen consumption and recovery energy expenditure between high intensity interval aerobic exercise (HIIT) and continuous aerobic exercise in adult amateur runners. Methods: The study included 10 runners, with a mean age of 35.7 ± 5.87 years, height 1.69 ± 0.11 m; body mass 74.13 ± 11.26 kg; fat percentage 19.31 ± 4.27% and maximal oxygen consumption (VO2max) of 3.50 ± 0.64 l/kg/min-1. The continuous aerobic exercise protocol consisted of 20 minutes of running with intensity of 70-75% HRmax. Two 20-second cycles of 8 sprints were performed for HIIT at the highest possible speed, with 10 seconds of rest and a 3-minute interval between cycles. The sample group performed the two protocols at least 48 hours and at most one week apart. EPOC was observed using ergospirometry after the running protocols, and mean consumption was analyzed between 25-30 minutes after exercise. Oxygen consumption at 9-10 minutes was used for resting consumption. The study has a cross-sectional experimental design. Results: Oxygen consumption of 0.57 ± 0.29l/kg/min1 and energy expenditure of 2.84 ± 1.44 kcal/min were observed for continuous aerobic exercise, with values of 0.61 ± 0.62 l/kg/min−1 and 3.06 ± 1.10 kcal/min respectively (p <0.05) for HIIT. Conclusion: The protocols performed did not show a statistically significant difference in terms of EPOC and energy expenditure, but the performance of HIIT increased lipid metabolism for exercise recovery, which may favor the weight loss process. Moreover, this activity model takes up less time. Level of evidence I, randomized clinical trial.

The Effects of a Proprietary Resistance Garment Technology on Exercise and Recovery Energy Expenditure

The Effects of a Proprietary Resistance Garment Technology on Exercise and Recovery Energy Expenditure

Influence of Interval vs Continuous Exercise on Markers of Metabolic Rate During Exercise and Recovery

Studies have shown that improvements in body composition after interval training are equivalent or superior to those resulting from continuous, moderate-intensity exercise training, although time and energy expenditure associated with interval training is lower. PURPOSE: To compare exercise and 3-hour recovery VO2, energy expenditure (EE), core temperature, and heart rate (HR), associated with 40 minutes of continuous, moderate-intensity exercise (50-60% of heart rate reserve [HRR]) (CON) with those associated with three models of interval training: 4 (I-4), 7 (I-7), and 10 (I-10), one-minute bouts of exercise at ~90% of maximal heart rate alternated with 1-minute recovery bouts at ~ 50-60% of HRR. METHODS: Nine healthy adults (5 females, 4 males, 23.8 ± 2.8 years, 75.0 ± 9.9 kg) underwent a submaximal exercise test to determine estimated VO2 max. Exercise sessions were then completed in random sequence at least one week apart. RESULTS: Exercise VO2 was 66.0 ± 12.2 L for CON, 17.0 ± 2.9 L for I-4, 30.4 ± 6.9 L for I-7, and 44.3 ± 10.4 L for I-10. EE for each exercise session was 323.5 ± 60.1 kcal for CON, 84.2 ± 19.5 kcal for I-4, 151.0 ± 33.7 kcal for I-7, and 219.5 ± 51.4 kcal for I-10. Average exercise HR was 133.8 ± 4.1 for CON, 142.2 ± 8.2 for I-4, 152.4 ± 5.8 for I-7, and 152.4 ± 5.7 for I-10. Recovery HR in first hour after exercise was higher after I-10 (82.3 ± 6.4 beats/min) than after CON (75.4 ± 8.4 beats•min-1) and I-4 (76.8 ± 7.3 beats•min-1). Recovery HR in 2nd hour after exercise was higher after I-10 (70.8 ± 8.1 beats•min-1) than after CON (66.7 ± 6.7 beats•min-1) or I-4 (67.7 ± 6.9 beats•min-1). Rate of EE was lower in 2nd hour after exercise for CON (1.04 ± 0.15 kcal•min-1) than after I-10 (1.10 ± 0.15 kcal•min-1) or I-4 (1.11 ± 0.18 kcal•min-1). CONCLUSIONS: Though exercise VO2 and EE associated with CON were significantly higher than those associated with any of the interval training sessions, several markers of metabolic rate (HR, EE) were higher during recovery after I-10 than after CON. Differences in the recovery periods after interval training vs CON may partially explain reports that interval training results in similar or greater improvements in body composition when compared with continuous exercise, even with significantly lower exercise energy expenditure.

Milk consumption following exercise reduces subsequent energy intake in female recreational exercisers.

The aim of this study was to evaluate the effects of skimmed milk as a recovery drink following moderate–vigorous cycling exercise on subsequent appetite and energy intake in healthy, female recreational exercisers. Utilising a randomised cross-over design, nine female recreational exercisers (19.7 ± 1.3 years) completed a test followed by two main exercise trials. The main trials were conducted following a standardised breakfast. Following 30 min of moderate-vigorous exercise (65% ), either 600 mL of skimmed milk or 600 mL of orange drink (475 mL orange juice from concentrate, 125 mL water), which were isoenergetic (0.88 MJ), were ingested, followed 60 min later with an ad libitum pasta meal. Absolute energy intake was reduced 25.2% ± 16.6% after consuming milk compared to the orange drink (2.39 ± 0.70 vs. 3.20 ± 0.84 MJ, respectively; p = 0.001). Relative energy intake (in relation to the energy content of the recovery drinks and energy expenditure) was significantly lower after milk consumption compared to the orange drink (1.49 ± 0.72 vs. 2.33 ± 0.90 MJ, respectively; p = 0.005). There were no differences in AUC (× 1 h) subjective appetite parameters (hunger, fullness and desire to eat) between trials. The consumption of skimmed milk following 30 min of moderate-vigorous cycling exercise reduces subsequent energy intake in female recreational exercisers.

Validity of the SenseWear Armband to Assess Energy Expenditure During Intermittent Exercise and Recovery in Rugby Union Players

Portable wearable devices that assess energy expenditure during intermittent exercise and recovery would be useful in team sports. Fourteen state-level male rugby union players (mean ± SD: age, 22 ± 4 years; body mass, 88.8 ± 11.2 kg; height, 1.81 ± 0.07 m, body fat, 18 ± 6%) participated in this study. Energy expenditure was measured by the SenseWear Armband (SWA) and validated against indirect calorimetry as the criterion measure during a 42-minute rugby-specific intermittent exercise test and an immediate postexercise 10-minute recovery period. Energy expenditure measurements from indirect calorimetry and the SWA were only moderately correlated during both the exercise test (r = 0.55, ±0.34; mean, ±90% confidence limits) and recovery period (r = 0.58, ±0.33). The SWA estimate of energy expenditure during exercise was unclear, with a mean bias of -1.9% (±5.3%), and during recovery energy expenditure was overestimated, with a mean bias of 17% (±12%) at the mean estimated energy expenditure. Typical error of SWA energy expenditure estimates expressed as a coefficient of variation (±90% confidence interval) was 10% (8-16%) during exercise and 19% (14-30%) during recovery. The SWA did not provide a valid measure of energy expenditure during rugby-specific intermittent exercise or 10-minute postexercise recovery. Further improvements are required in the performance of the SWA before it can be used routinely in intermittent sports and provide worthwhile information in relation to workloads of athletes for sport scientists and coaches.

Aerobic, Anaerobic, and Excess Postexercise Oxygen Consumption Energy Expenditure of Muscular Endurance and Strength: 1-Set of Bench Press to Muscular Fatigue

We use a new approach to the estimation of energy expenditure for resistance training involving nonsteady state measures of work (weight × displacement), exercise O2 uptake, blood lactate, and recovery O2 uptake; all lifts were performed to muscular failure. Our intent was to estimate and compare absolute and relative aerobic and anaerobic exercise energy expenditure and recovery energy expenditure. Single-set bench press lifts of ∼ 37, ∼ 46, and ∼ 56% (muscular endurance-type exercise) along with 70, 80, and 90% (strength-type exercise) of a 1 repetition maximum were performed. Collectively, the muscular endurance lifts resulted in larger total energy expenditure (60.2 ± 14.5 kJ) as compared with the strength lifts (43.2 ± 12.5 kJ) (p = 0.001). Overall work also was greater for muscular endurance (462 ± 131 J) as opposed to strength (253 ± 93 J) (p = 0.001); overall work and energy expenditure were related (r = 0.87, p = 0.001). Anaerobic exercise and recovery energy expenditure were significantly larger for all strength lifts as compared with aerobic exercise energy expenditure (p < 0.001). For the muscular endurance lifts, anaerobic energy expenditure was larger than recovery energy expenditure (p < 0.001) that in turn was larger than aerobic exercise energy expenditure (p < 0.001). We conclude that for a single set of resistance training to fatigue, the anaerobic and recovery energy expenditure contributions can be significantly larger than aerobic energy expenditure during the exercise. To our surprise, recovery energy expenditure was similar both within strength and muscular-endurance protocols and between protocols; moreover, recovery energy expenditure had little to no relationship with aerobic and anaerobic exercise energy expenditure or work.

Quantifying the Immediate Recovery Energy Expenditure of Resistance Training

As opposed to steady state aerobic-type exercise involving long duration, continuous, rhythmic, large muscle group activities that consume large volumes of oxygen, a resistance training set is brief, intermittent, uses multiple and isolated muscles, and is considered anaerobic in description. Because differences are evident between aerobic- and anaerobic-type exercise, it is proposed that the methods used for estimating resistance training energy expenditure should be different as compared with walking, jogging, cycling, etc. After a single set of weight lifting, for example, oxygen uptake is greater in the recovery from lifting as opposed to during the actual exercise; likewise, the anaerobic energy expenditure contribution to lifting may exceed exercise oxygen uptake. Recovery energy expenditure also does not appear well related to the anaerobic energy expenditure of the previous exercise. Based on this evidence, it is suggested that anaerobic-type exercise should not be based on aerobic-type models. In terms of excess postexercise oxygen consumption, a hypothesis is presented in regard to how non-steady-state energy expenditure in the immediate recovery from intense exercise should be properly quantified (e.g., in-between resistance training sets). The proposed concept is based on possible substrate or fuel use differences during intense exercise and aerobic recovery and the biochemistry and bioenergetics of glucose, lactate, and fat oxidation. It is proposed that immediately after a single weight lifting bout or in-between resistance training sets, as O2 uptake plummets rapidly back toward pre-exercise levels, a separate energy expenditure conversion is required for recovery that differs from non-steady-state exercise, that is, 1 L of recovery oxygen uptake = 19.6 kJ (4.7 kcal) (not the standard exercise conversion of 1 L of oxygen uptake = 21.1 kJ) (5.0 kcal).

Influence of resistance exercise volume on recovery energy expenditure in women

The acute effects of resistance exercise on energy expenditure in the post-exercise period have not been well studied in women, even though they are at high risk for weight gain and so would benefit greatly from exercise-related increases in energy expenditure. The purpose of this study was to identify factors that influence recovery energy expenditure in women after an acute bout of resistance exercise. Seventeen healthy women aged 40–55 years completed an acute bout of resistance exercise followed by measurement of energy expenditure for 120 min of recovery. Body composition was measured via air displacement plethysmography. The resistance exercise bout consisted of three sets of 8–12 repetitions of eight exercises at 50% of one-repetition maximum (1-RM) for the first set and 80% 1-RM for the second and third sets. Oxygen consumption (VO2) was measured before and for 120 min after resistance exercise. Post-exercise energy expenditure data were analysed as 4-min means at 0, 20, 40, 60, 90, and 120 min of recovery. Mean (± s x ) training volume was 7604.1±450.64 kg and overall mean recovery energy expenditure was 133±6 kcal. Pearson's correlation analysis found no significant relationship between post-exercise energy expenditure and age, body mass index, exercise time or delay between cessation of exercise and commencement of metabolic measurement. Absolute (kg) lean mass was also not significantly related to energy expenditure at any time post-exercise, although relative (%) lean mass was during the late recovery period only (40 min of recovery: r = 0.49, P = 0.05; 60 min: r = 0.51, P = 0.04; 90 min: r = 0.63, P < 0.01). The factor most consistently related to post-exercise energy expenditure was total exercise volume, which had a moderately strong relationship through 90 min of the recovery period (0 min of recovery: r=0.49. P = 0.05; 20 min: r = 0.52, P = 0.03; 40 min: r = 0.53, P = 0.03; 60 min: r = 0.50, P = 0.04; 90 min: r=0.48, P = 0.05). In the present sample of women, acute post-exercise energy expenditure was influenced primarily by total training volume, although lean mass had a limited effect. Based on these findings, it is recommended that women be encouraged to lift at higher intensities (70–80% 1-RM) to maximize post-exercise energy expenditure and potentially promote fat loss.

Energy Expenditure And Fat Utilization During And After Interval Versus Continuous Self-paced Exercise Bouts

PURPOSE: Exercise is often performed to achieve high energy expenditure (EE) and fat oxidation (FO). The purpose of the study was to compare exercise EE, early recovery EE (REE), and total FO during self-paced "hard interval" vs "talking intensity" continuous exercise bouts typical of fitness industry exercise prescriptions. METHODS: After preliminary testing, 9 regularly active males (age 28 ± 6 yr, VO2max 55 ± 5 ml·min-1·kg-1) performed a self-paced high intensity interval session (INT) consisting of six, 4 min work bouts interspersed by 2 min recovery periods (34 min total exercise time) with continuous gas exchange measurement during the 34 min exercise session and for 30 min post exercise. Responses were compared with those measured during a "talking intensity" exercise bout of identical total duration (SS). The two bouts were performed in randomized order. EE, REE, and FO were estimated from continuous measurements of respiratory gas exchange. Fat oxidation calculations are considered minimum estimates due to presumed contamination of CO2 production with CO2 release due to H+buffering. RESULTS: The INT session elicited higher average heart rate (171 ± 14 vs 154 ± 15, p<0.001), blood lactate concentration (6.5 ± 2.8 vs 2.1 ± 1.1 mmol·L-1, p<0.001), and RPE (17 ± 1 vs 12 ± 1, p<0.001) than the SS session. EE during INT was ∼12% higher (555 ± 75 vs 495 ± 68 kcal, p<0.01) and 30min REE was 23% higher (89 ± 15 vs 72 ± 9 kcal, p<0.01). FO during 34 min exercise tended to be higher in SS (13.0 ± 5.3 vs 9.4 ± 4.5 g, p = 0.12). FO during the first 30 min post-exercise was higher after INT (4.5± 1.4 vs 2.5 ± 1.3 g. p = 0.02). Total FO (34 min exercise+30 min recovery) was similar in the interval based and continuous exercise sessions (13.0 ± 3.7 vs 15.5 ± 6.4 g, p= 0.56). CONCLUSIONS: In this study, we have attempted to simulate two exercise prescriptions typical of the time constraints and intensity goals of "1 hour fitness classes". Our results suggest that for the same time investment, self-paced interval training results in significantly greater total energy expenditure and similar total fat oxidation than continuous exercise performed at "talking intensity."

The Effect of Varying Intensity on Total Energy Expenditure During Circuit Weight-Training with Equal Volume

In studies involving total energy expenditure (net exercise VO2 + net recovery VO2) during circuit weight-training, few have focused on the effect of variable training intensities, in which the training volumes (intensity X sets X repetitions) are equal. PURPOSE: This study was designed to test the potential differences in total energy expenditure (TEE) following circuit weight-training under two different intensities, in which the sets and repetitions were adjusted to keep training volumes equal. METHODS: Thirteen physically active, college-age males and females (males = 4; females = 9; mean age = 20.7 yr.) were tested using a 3-station weight-training circuit (seated chest-press, supine leg-press, and seated lat pull down), minimum 3 sets, with one minute between sets, under two intensities (70% and 85% of 1RM). Training volumes were equated for total pounds lifted by adjusting the intensity, sets, and repetitions during each trial. Trials were conducted in random order, on separate days, with a minimum of 48 hr between each. VO2 was monitored using a Cosmed™ K4b2 portable system for 15 minutes pre-exercise (resting), during exercise, and post-exercise until VO2 returned to resting values. Energy expenditure was calculated from VO2using indirect calorimetry, in which 1 liter of oxygen consumed equals 5 kcal of energy. RESULTS: TEE values were significantly higher during 85% intensity trials (60.25 ± 6.33 kcal) than 70% trials (54.23 ± 5.60 kcal) with higher repetitions in the latter equalizing training volume (P = 0.024). When breaking TEE down into net exercise and net recovery energy expenditures, recovery energy expenditure was a significantly larger contributing factor in TEE. Recovery energy expenditure was 12.28 ± 6.3 kcal at 85% intensity, and 9.77 ± 5.4 kcal at 70% intensity (P = .029) CONCLUSIONS: These results suggest that heavier resistance with fewer repetitions creates a greater recovery O2 demand and thus greater TEE, than lower resistance with more repetitions, despite equal training volumes.

Effect of Protein Ingestion on Energy Expenditure and Substrate Utilization after Exercise in Middle-Aged Women

Research suggests that ingesting protein after resistance exercise (RE) increases muscle protein synthesis and results in greater muscle gains. The effect on energy expenditure and substrate utilization, however, is unclear. This study evaluated the effect of RE and postexercise protein on recovery energy expenditure and substrate utilization in 17 women (age 46.5 +/- 1.2 y). A whey-protein supplement (120 kcal, 30 g protein) was ingested immediately after 1 bout of RE (PRO) and a noncaloric placebo after another (PLA).VO2 and respiratory-exchange ratio (RER) were measured before and for 120 min after each exercise session. RE resulted in a significant increase in VO2 that persisted through 90 min of recovery (P < 0.01) and was not affected by protein supplementation. RE significantly lowered RER, resulting in an increase in fat oxidation for both PLA and PRO (P < 0.01). For PRO, however, RER returned to baseline values earlier than for PLA, resulting in a reduced fat-oxidation response (P = 0.02) and earlier return to preexercise baseline values than for PLA. Substrate utilization was significantly different between conditions (P = 0.02), with fat contributing 77.76% +/- 2.19% for PLA and 72.12% +/- 2.17% for PRO, while protein oxidation increased from 17.18% +/- 1.33% for PLA to 20.82% +/- 1.47% for PRO. Postexercise protein did not affect energy expenditure, but when protein was available as an alternate fuel fat oxidation was diminished. Based on these findings it might be beneficial for middle-aged women to delay protein intake after RE to maximize fat utilization.

Resting, Exercise and Recovery Energy Expenditure and RQ Differences in Females with Bulimia Nervosa vs. Comparable-Mass Controls

Resting, Exercise and Recovery Energy Expenditure and RQ Differences in Females with Bulimia Nervosa vs. Comparable-Mass Controls

Resistance Training Volume and Post Exercise Energy Expenditure

The main purpose of this study was to determine if increasing the volume of a resistance training program, while keeping the intensity the same would significantly increase the recovery energy expenditure, as measured by the excess post-exercise energy expenditure (EPEE). Fifteen resistance-trained women completed two resistance training protocols. Both protocols consisted of nine exercises performed to volitional fatigue, at the previously determined eight RM. The only difference between the two protocols was the number of sets (1-set or 3-sets). All subjects completed both protocols in a randomized and counterbalanced fashion. Energy expenditure, as determined by oxygen consumption and respiratory exchange ratio (RER), was measured continuously prior to exercise, during the exercise session, and during the entire 120 min of recovery. Fingertip blood lactate concentration was determined at baseline, immediately post-exercise, and every 30 min in recovery. The net energy expenditure during exercise was significantly greater during the 3-set protocol (661.9 +/- 43.9 kj) than the 1-set protocol (234.7 +/- 13.4 kj). However, per minute of exercise, there was no significant difference between the two protocols. During the 120 min of recovery, the net EPEE was not significantly different between the two protocols (93.3 +/- 20.1 kj following the 1-set protocol, and 94.1 +/- 7.1 kj following the 3-set protocol). However, when comparing the EPEE to the number of minutes spent in the exercise session, the 1-set protocol led to a significantly greater energy expenditure in the recovery period (1.0 +/- 0.22 kj/min) than did the 3-set protocol (0.4 +/- 0.03 kj/min). These data indicate that in previously trained women, increasing the volume of resistance training, from 1-set to 3-sets, while keeping the intensity the same will not significantly increase EPEE above what is found in a lower volume of work.

Direct and indirect calorimetry of lactate oxidation: implications for whole-body energy expenditure

Whole-body energy expenditure for heavy/severe exercise is currently accounted for by either: (1) anaerobic and oxygen uptake measures during exercise where recovery energy expenditure is omitted; or (2) oxygen uptake during, and an EPOC (excess post-exercise oxygen consumption), measure following exercise where substrate level phosphorylation during exercise is considered part of EPOC. Simultaneous direct/indirect calorimetry enabled us to determine if a thermodynamic reversal (i.e. heat consumption) takes place as the highly exothermic pyruvate to lactate reaction proceeds in the opposite direction. Reversibility implies that oxygen uptake (e.g. EPOC) can indeed account for rapid glycolytic ATP production regardless if lactate is formed or not (e.g. 1.2 g glucose catabolism = 20.9 kJ · l O2 - 1). Cultured hybrid cells and mouse cardiac muscle fibres were utilized in simultaneous calorimetry and respirometry experiments where pyruvate or lactate was predominantly oxidized. The calorimetric to respiratory ratio was determined using heat flux (pW · cell - 1) and oxygen flux (pmol · s - 1 · cell - 1) measures. Ten cell experiments gave calorimetric to respiratory ratios that showed no statistical difference (P = 0.97) whether cells respired predominantly on lactate (−516 ± 53 kJ · mol O2 - 1) or pyruvate (−517 ± 89 kJ · mol O2 - 1). In three cardiac preparations, the calorimetric to respiratory ratio was - 502 ± 15 kJ · mol O2 - 1 for lactate and - 506 ± 47 kJ · mol O2 - 1 for pyruvate, again a non-significant difference (P = 0.91). Heat consumption did not occur during lactate oxidation. These results suggest that rapid glycolytic ATP and lactate production, and lactate oxidation, are both independently associated with heat production and thus represent separate and additive components to the measurement of total energy expenditure for exercise and recovery.

THE EFFECT OF STEADY-STATE VERSUS INTERVAL EXERCISE ON EXCESS POST-EXERCISE OXYGEN CONSUMPTION

Following exercise, oxygen consumption (VO2) is elevated for some period of time. The magnitude and duration of the elevated VO2 is most influenced by exercise intensity and duration. PURPOSE To compare the effects of steady-state (SS) and interval (INT) running on excess post-exercise oxygen consumption (EPOC) when caloric expenditure of bouts was held constant. METHODS Twelve trained men (29.8 ± 3.7 yr, 77.6 ± 8.4 kg, and 64.7 ± 7.7 ml/kg/min) expended 300 kcal of energy while running at a steady-state intensity of 60% VO2max versus alternating in 5 minute intervals between 50% and 70% VO2max in a counter-balanced design on separate days. Variables measured included VO2, heart rate (HR), and respiratory exchange ratio (RER). Recovery measurements were taken as the participant remained in a seated position until his VO2 returned to pre-exercise baseline, or 1-hour, whichever occurred first. Exercise trials were analyzed using two-way ANOVA with repeated measures. RESULTS No differences were found between exercise trials in recovery VO2, HR, or RER. Total EPOC (L) was 2.2 ± 0.55 and 2.4 ± 0.61 for SS and INT trials, respectively (p = 0.802). Recovery energy expenditure was also similar between exercise trials with 11 ± 2.65 and 12 ± 2.93 kcal for SS and INT trials, respectively (p = 0.802). Six participants in SS and 4 in INT had elevated VO2 at the 1-h cut-off point. Of those who did return to baseline prior to 1-h, EPOC duration was 16.75 ± 2.4 min (SS) and 24.25 ± 3.8 min (INT) (p = 0.149). Including those who did not return to baseline by 1-h, EPOC duration was 38.4 ± 6.62 min (SS) and 36.2 ± 5.65 min (INT) (p = 0.802). CONCLUSION It was concluded that both SS and INT did not cause substantial EPOC during the first hour post-exercise. Furthermore, both trials led to similar recovery energy expenditure.

POST EXERCISE METABOLIC RATE FOLLOWING DOWNHILL RUNNING

An acute eccentric exercise bout produces muscle damage and delayed onset muscle soreness (DOMS). Both are attenuated following a subsequent eccentric exercise bout indicating that an adaptation occurs. The degree to which this type of exercise influences recovery energy expenditure is unknown. PURPOSE: We investigated whether excess postexercise oxygen consumption (EPOC) measured for 2h and resting metabolic rate (RMR) measured 24h (day 2) and 48h (day 3) post-exercise would differ following level vs downhill treadmill running. METHODS: Eight untrained male subjects performed three 40min submaximal exercise trials eliciting ∼70% VO2max: a level running trial and two downhill running trials (DH1 and DH2). DH1 was performed 1wk after level, and DH2 2wk after DH1. Testing occurred in the morning following an overnight fast and no strenuous exercise for the previous 36h. Baseline RMR was measured for 30min pre-exercise. DOMS was rated for five lower body sites at 24h and 48h post exercise. Analyses included 1- and 2-way ANOVA and Friedman tests. RESULTS: When compared to baseline, VO2 was significantly elevated at 60 (p < .01) and 90min (p < .03) for DH1 and at 60min (p < .03) for DH2, whereas VO2 was not significantly elevated at any of these time points during the level trial. However, there was no significant difference in the accumulated 2h EPOC among trials (level = 7.04/5.32, DH1 = 8.55í4.12, and DH2 = 8.38í2.89 L). RMR was not significantly different among days or among trials. DH1 produced significantly greater DOMS than level running (p < .01) at all 5 sites. CONCLUSION: It can be concluded that the first bout of downhill running for 40min at a moderately high intensity, which produced a significant amount of DOMS, resulted in a prolonged EPOC (> 90min). However, an elevated metabolic rate was not detected 24 or 48th following exercise when DOMS was evident. In contrast, metabolic rate returned to the resting value within 1h after running on a level grade. The physiological mechanisms involved in producing a prolonged elevation in metabolic rate following downhill running remain to be elucidated.

Energy Expenditure of Heavy to Severe Exercise and Recovery

A method of indirect calorimetry is proposed that attempts to better quantify the energy expenditure associated with heavy/severe exercise and the recovery from that exertion. To accomplish this objective, the energy expenditure associated with rapid anaerobic glycolysis is separated from that of mitochondrial respiration both during and after heavy/severe exercise. This model contrasts with those hypotheses that employ oxygen uptake as the sole measure of energy expenditure (e.g. the oxygen debt) or that utilizing a measure of anaerobic energy expenditure while ignoring the recovery energy expenditure. Anaerobic metabolism and its energy promoting effect on oxidative recovery must be independently acknowledged regardless of the eventual fate of lactate.

Re-interpreting anaerobic metabolism: an argument for the application of both anaerobic glycolysis and excess post-exercise oxygen comsumption (EPOC) as independent sources of energy expenditure.

Due to current technical difficulties and changing cellular conditions, the measurement of anaerobic and recovery energy expenditure remains elusive. During rest and low-intensity steady-state exercise, indirect calorimetric measurements successfully represent energy expenditure. The same steady-state O2 uptake methods are often used to describe the O2 deficit and excess post-oxygen consumption (EPOC): 1 l O2 = 5 kcal = 20.9 kJ. However, an O2 deficit plus exercise O2 uptake measurement ignores energy expenditure during recovery, and an exercise O2 uptake plus EPOC measurement misrepresents anaerobic energy expenditure. An alternative solution has not yet been proposed. Anaerobic glycolysis and mitochondrial respiration are construed here as a symbiotic union of metabolic pathways, each contributing independently to energy expenditure and heat production. Care must be taken when using O2 uptake alone to quantify energy expenditure because various high-intensity exercise models reveal that O2 uptake can lag behind estimated energy demands or exceed them. The independent bioenergetics behind anaerobic glycolysis and mitochondrial respiration can acknowledge these discrepancies. Anaerobic glycolysis is an additive component to an exercise O2 uptake measurement. Moreover, it is the assumptions behind steady-state O2 uptake that do not permit proper interpretation of energy expenditure during EPOC; 1 l O2 not = 20.9 kJ. Using both the O2 deficit and a modified EPOC for interpretation, rather than one or the other, leads to a better method of quantifying energy expenditure for higher intensity exercise and recovery.

AGE AND EXCESS POSTEXERCISE OXYGEN CONSUMPTION 74

It has been well-documented that metabolic rate both at rest and during maximal intensity exercise declines as one ages. However, energy expenditure during recovery from exercise has not been studied. We examined the magnitude and duration of excess postexercise oxygen consumption (EPOC) in three age groups, i.e., 18-25 yr (Y), 35-45 yr (M), and 55-67 yr (O). Volunteers were 45 men considered to be at low risk for cardiovascular disease according to ACSM(1995) guidelines and were evenly distributed among the age groups. They reported to the lab in the early morning after an overnight fast and refraining from strenuous physical activity for 36 h. Baseline VO2 was measured during the last 10 min of a 30 min seated rest. Subjects walked on a treadmill at 4.8 km h-1 until they expended 837 kJ (200 kcal). Grade was adjusted so that intensity was 60% of their measured VO2 max. Following a 1 min cool down at 2.7 km h-1 and 0% grade, subjects were seated until a 5 min average of VO2 was within ±.01 1 min-1 of the baseline value. ANOVA (Tukey post hoc) showed that VO2 max (ml kg-1 min-1) was higher (p<.001) in Y(X=53.7±7.2 SD) than M (45.5±8.6) and O (38.8±9.9). Baseline VO2 was significantly higher (p<.04) in Y (3.7±0.5) than O (3.2±0.6) but not M (3.3±0.5). EPOC duration (min) was similar among the groups (Y=24.9±10.4, M=23.3±9.9. O=21.3±11.8), however, Y had a greater (p<.03) EPOC magnitude(57.8±33.1 kJ) than M (39.3±19.3) and O (33.5±18.8). The findings indicate that the time it takes to recover from moderate intensity and duration exercise does not differ across age groups. However, energy expended during the EPOC period was diminished across the age span, implying that the rate of recovery energy expenditure may slow as one ages. Additionally, our results agree with what has been previously reported regarding the decrease in VO2 at rest and during maximal exercise across age groups. More work should be done to substantiate these findings.

Prolonged Recovery From Eccentric Versus Concentric Exercise

In order to determine whether exercise mode affects recovery energy expenditure, 7 active men (average age 25 yrs) performed a control rest and three submaximal exercise bouts in counterbalanced order in separate weeks. The bouts, designed to involve three levels of eccentric muscular activity, included 60% VO2max jog (60 J), 60% downhill (-5%) jog (60 DH), 60% cycling (60 C), and a control session. Following a 24-hr period of regulated activity and diet, subjects exercised for 60 min. VO2 and RER were assessed during 48 hrs of regulated recovery. Total energy use was elevated following 60 C and 60 DH versus control, and fat energy use was elevated following 60 J, 60 DH, and 60 C versus control. For combined trials, the total energy use was higher at 1, 2, and 9 hrs postexercise. These results do not support the hypothesis that eccentric muscular activity affects the magnitude of recovery energy expenditure.