Resistance exercise induces a greater irisin response than endurance exercise.

OBJECTIVE: We determined detailed time-course changes in the irisin response to acute exercise using different exercise modes. METHODS: In experiment 1, seven healthy males rested for 12h (8:00-20:00) to determine the diurnal variation in plasma irisin concentration. In experiment 2, 10 healthy males conducted three exercises to clarify time-course changes in plasma irisin concentration over 6h, using a randomized crossover design. The resistance exercise (R) trial consisted of eight exercises of 12 repetitions with 3-4 sets at 65% of one repetition maximum (1RM). The endurance exercise (E) trial consisted of 60 min of pedaling at 65% of maximal oxygen uptake (VO2max). In the combined mode (R+E) trial, 30 min of endurance exercise was preceded by 30 min of resistance exercise. RESULTS: In experiment 1, no significant changes in plasma irisin concentration were observed over 12h. In experiment 2, the R trial showed a marked increase in plasma irisin concentration 1h after exercise (P<0.05), but not in the E or R+E trials. The area under the curve (AUC) for irisin concentrations for 6h after exercise was significantly higher in the R trial than in the R+E trial (P<0.05). The AUC for irisin concentrations was significantly correlated with AUC values for blood glucose, lactate, and serum glycerol (r=0.37, 0.45, 0.45, respectively. P<0.05). CONCLUSIONS: Resistance exercise resulted in significantly greater irisin responses compared with endurance exercise alone, and resistance and endurance exercises combined.

A single versus multiple bouts of moderate-intensity exercise for fat metabolism.

This study compared the fat metabolism between 'a single bout of 30-min exercise' and 'three bouts of 10-min exercise' of the same intensity (60% maximal oxygen uptake) and total exercise duration (30 min). Nine healthy men participated in three trials: (1) a single 30-min bout of exercise (Single), (2) three 10-min bouts of exercise, separated by a 10-min rest (Repeated) and (3) rest (Rest). Each exercise was performed with a cycle ergometer at 60% of maximal oxygen uptake, followed by 180-min rest. Blood lactate concentration increased significantly after exercise in the Single and Repeated trials (P < 0.05), but the Single trial showed a significantly higher value during the recovery period (P < 0.05). No significant difference was observed in the responses of plasma glycerol concentration. The Repeated trial produced a smaller increase in the ratings of perceived exertion during the exercise (P < 0.01). During the exercise, no significant difference was observed in respiratory exchange ratio (RER) between the Single and Repeated trials. However, the RER values during the recovery period were significantly lower in the Repeated trial than in the Single and Rest trials (P < 0.05), indicating higher relative contribution of fat oxidation in the Repeated trial (P < 0.05). These results suggest that the repetition of 10-min of moderate exercise can contribute to greater exercise-induced fat oxidation compared with a single 30-min bout of continuous exercise.

Hormonal responses to resistance exercise after ingestion of carnosine and anserine.

Intramuscular carnosine buffers protons (H+) in skeletal muscle. We examined the effects of supplementation with chicken breast meat extract (CBEX) containing carnosine and anserine on hormonal responses to resistance exercise. Twenty-two men were assigned to a CBEX drink group (CBEX containing total 2 g of carnosine and anserine) (n = 14) or a placebo drink group (n = 8). The subjects ingested the prescribed drink (100 mL) twice daily for 30 days without physical training. Before and after the supplementation period, the subjects completed 5 sets of bilateral knee extension exercises (with a 90-s rest between sets). The magnitude of the increase in exercise-induced free testosterone did not change significantly after supplementation in either group. The blood lactate response to exercise was attenuated after supplementation in both groups (p < 0.05). In the CBEX group, the plasma epinephrine and norepinephrine concentrations after exercise were significantly lower after supplementation (p < 0.05). The serum growth hormone response to exercise was also reduced in the CBEX group after supplementation (delta value: 5.4 ± 1.9 ng/mL [pre] vs. 1.6 ± 0.5 ng/mL [post], p = 0.05). No significant differences in exercise-induced strength reduction (fatigue index) were observed in the 2 groups after supplementation. These results suggest that short-term supplementation with CBEX attenuates the exercise-induced epinephrine, norepinephrine, and growth hormone responses.

Hormonal and metabolic responses to slow movement resistance exercise with different durations of concentric and eccentric actions.

We examined hormonal responses to slow movement exercise involving concentric (CON) and eccentric (ECC) actions. Nine men performed knee extension exercises: (1) low-intensity exercise with slow CON contractions (5-1; 5 s for CON and 1 s for ECC); (2) low-intensity exercise with slow ECC contractions (1-5; 1 s for CON and 5 s for ECC); (3) low-intensity exercise with slow CON and ECC contractions (3-3; 3 s for each contraction); and (4) high-intensity exercise at normal velocity (1-1; 1 s for each contraction). Lactate concentration was significantly higher after the 5-1 than after the 1-5 (P < 0.05). Slow movement exercises significantly raised the concentrations of plasma epinephrine, serum growth hormone, and free testosterone (P < 0.05). Serum growth hormone concentration increased to a greater extent after the three slow movement trials compared with the normal movement trial (1-1). However, serum cortisol concentration was significantly higher after the 5-1 than after the 1-5 and 1-1 (P < 0.05). Average V(O)(2) throughout the exercise session (divided by the time to complete exercise session) was significantly higher in the 1-1 (P < 0.05), with no significant difference among the slow movement trials. In conclusion, low-intensity exercises with slow movement acutely increased anabolic hormone concentrations regardless of the time to complete CON and ECC actions. In contrast, low-intensity exercise with slower ECC action stimulated smaller changes in lactate and cortisol compared with low-intensity exercise with slower CON action.

Hormone and recovery responses to resistance exercise with slow movement.

This study examined acute hormone and recovery responses to resistance exercise with slow movements. Six men performed three types of exercise regimens (five sets of knee extension exercise): (1) high-intensity resistance exercise with normal movement (HN; 1 s for lifting action, 1 s for lowering action), (2) low-intensity resistance exercise with slow movement (LS; 3 s for lifting action, 3 s for lowering action), and (3) low-intensity resistance exercise with normal movement (LN; 1 s for lifting action, 1 s for lowering action). The intensity in the first set was set at approximately 80% of 1RM for HN and 40% of 1RM for LS and LN. In the HN and LS, the subjects performed each exercise set until exhaustion. In the LN, both intensity and number of repetitions were matched with those for LS. The total work volume in the HN showed approximately double the value of LS and LN (P < 0.05). Electromyography (EMG) data indicated that LS showed sustained EMG signals throughout the exercise. During the exercise, the HN and LS showed lower muscle oxygenation levels. After the exercise, LS caused significantly greater norepinephrine and free testosterone responses (delta value) than in the HN and LN (P < 0.05). However, no significant difference was observed in the recovery of maximal isometric strength, isokinetic strength, and jump performance between the HN and LS. These results indicate that slow movements during the resistance exercise are important for the enhancement of hormonal responses, especially catecholamine and free testosterone, but they do not affect muscle strength recovery.

Effects of resistance exercise on lipolysis during subsequent submaximal exercise.

PURPOSE: This study examined effects of prior resistance exercise on fat metabolism during subsequent submaximal exercise with different recovery periods between exercise bouts. METHODS: Ten male subjects performed three types of exercise regimens: 1) submaximal endurance exercise only (E), 2) submaximal endurance exercise with prior resistance exercise and 20 min of rest (RE20), and 3) submaximal endurance exercise with prior resistance exercise and 120 min of rest (RE120). Resistance exercise consisted of six exercises, each with three to four sets at 10-repetition maximum. Subjects performed cycle ergometer exercise at 50% of the maximal oxygen uptake for 60 min. RESULTS: Prior resistance exercise caused increases in blood lactate, plasma norepinephrine, serum growth hormone (GH), insulin, and glycerol concentrations (P < 0.01). Before the submaximal exercise, serum free fatty acid (FFA) concentration was higher in the RE120 than in the RE20 and E trials (P < 0.01), although concentrations of plasma norepinephrine, serum GH, insulin, and glycerol were higher in the RE20 than in the RE120 and E trials (P < 0.05). Concentrations of FFA and glycerol during the 60-min submaximal exercise were higher in the RE120 and RE20 trials than in the E trial (P < 0.05). No significant difference was observed in the acetoacetate and 3-hydroxybutyrate responses. In the RE20 trial, fat oxidation throughout the 60-min submaximal exercise (mean value) was greater than in the E trial (P < 0.05), but no significant difference was found between the RE120 and E trials. CONCLUSION: Fat availability during the submaximal exercise was enhanced by prior resistance exercise. However, augmentation of fat oxidation was observed only in the trial with shorter rest between resistance exercise and submaximal exercise bouts (RE20 trial).

Enhancement of fat metabolism by repeated bouts of moderate endurance exercise.

This study compared the fat metabolism between "a single bout of prolonged exercise" and "repeated bouts of exercise" of equivalent exercise intensity and total exercise duration. Seven men performed three trials: 1) a single bout of 60-min exercise (Single); 2) two bouts of 30-min exercise, separated by a 20-min rest between exercise bouts (Repeated); and 3) rest. Each exercise was performed with a cycle ergometer at 60% of maximal oxygen uptake. In the Single and Repeated trials, serum glycerol, growth hormone, plasma epinephrine, and norepinephrine concentrations increased significantly (P<0.05) during the first 30-min exercise bout. In the Repeated trial, serum free fatty acids (FFA), acetoacetate, and 3-hydroxybutyrate concentrations showed rapid increases (P<0.05) during a subsequent 20-min rest period. During the second 30-min exercise bout, FFA and epinephrine responses were significantly greater in the Repeated trial than in the Single trial (P<0.05). Moreover, the Repeated trial showed significantly lower values of insulin and glucose than the Single trial. During the 60-min recovery period after the exercise, FFA, glycerol, and 3-hydroxybutyrate concentrations were significantly higher in the Repeated trial than in the Single trial (P<0.05). The relative contribution of fat oxidation to the energy expenditure showed significantly higher values (P<0.05) in the Repeated trial than in the Single trial during the recovery period. These results indicate that repeated bouts of exercise cause enhanced fat metabolism compared with a single bout of prolonged exercise of equivalent total exercise duration.

Attenuated growth hormone response to resistance exercise with prior sprint exercise.

PURPOSE: This study examined effects of prior sprint exercise on hormonal responses to subsequent resistance exercise with different recovery periods between exercise bouts. METHODS: Nine men performed three types of exercise regimens: 1) resistance exercise only (R), 2) resistance exercise with prior sprint exercise and 60 min of rest (SR60), and 3) resistance exercise with prior sprint exercise and 180 min of rest (SR180). Sprint exercises consisted of maximal sprint cycling (eight sets of 5-s sprints with 30-s rest periods between sets) with prior 10-min warm-up. Resistance exercise consisted of five exercises, each with three sets at a 10-repetition maximum with 1-min rest periods. RESULTS: Prior sprint exercise significantly increased blood lactate, glycerol, epinephrine, norepinephrine, growth hormone (GH), and free testosterone concentrations (P < 0.05). Before the resistance exercise, free fatty acids concentration was higher in the SR180 trial than in the SR60 and R trials (P < 0.05), whereas GH concentration was significantly higher in the SR60 trial (P < 0.01). After the resistance exercise, no significant difference was found in responses of pH, epinephrine, norepinephrine, and free testosterone among trials. The SR180 trial showed a smaller GH response (peak value: 7.8 +/- 1.6 (SE) ng.mL(-1)) than in the R trial (12.8 +/- 3.7 ng.mL(-1)), with no significant difference between trials. In the SR60 trial, GH response to resistance exercise was attenuated (3.3 +/- 1.2 ng.mL(-1), P < 0.01). Maximal strength and power measured immediately before the resistance exercise showed no difference among trials. CONCLUSION: These results indicate that GH response to resistance exercise was attenuated strongly when the exercise was preceded by sprint exercise and a shorter (60 min) recovery period.

Carnosine and anserine ingestion enhances contribution of nonbicarbonate buffering.

PURPOSE: The purpose of the present study was to investigate the effect of supplementation with chicken breast extract (CBEX), which was a rich source of carnosine and anserine, on acid-base balance and performance during intense intermittent exercise. METHODS: Eight male subjects performed intense intermittent exercise that consisted of 10 x 5-s maximal cycle ergometer sprints with a 25-s recovery period between each sprint. The subjects ingested 190 g of the test soup containing either CBEX or a placebo 30 min before the commencement of exercise. Arterial blood samples were collected at rest and during exercise to estimate the carnosine and anserine concentrations, pH, and bicarbonate concentration ([HCO3-]). RESULTS: Concentrations of anserine and its related amino acid significantly increased 30 min after CBEX supplementation, as compared with their values at rest. However, carnosine did not increase significantly. Following CBEX supplementation, the pH was significantly higher (P < 0.05) at the end of exercise, and [HCO3-] was also significantly higher (P < 0.05) during the latter half of exercise and after exercise. There were no significant differences in the total power and mean power of each set between the CBEX and placebo supplemented groups. CONCLUSION: Although oral supplementation with CBEX (which is a rich source of carnosine and anserine) increased the contribution of the nonbicarbonate buffering action and decreased bicarbonate buffering action in blood, intense intermittent exercise performance did not improve significantly.

Hormone and lipolytic responses to whole body vibration in young men.

This study examined the effects of whole-body vibration (WBV) on the hormone and lipolytic responses. Eight male subjects performed WBV and control (CON) trials on separate days. The WBV session consisted of 10 sets of vibration for a duration of 60 s with rest periods of 60 s between each set (frequency 26 Hz). The subjects maintained a static squat position with knees bent on the platform. In the CON trial, the WBV stimulation was not imposed. Blood samples were collected before both trials and during the recovery period. In the WBV trial, the concentrations of plasma epinephrine (Epi) and norepinephrine (NE) increased immediately after the session (P < 0.05). Serum free fatty acids (FFA) concentration increased significantly at the 150, 180, and 210 min points of the recovery period in the WBV trial (P < 0.01) with the interaction between trial and time (P < 0.01). Serum glycerol showed no significant change in either trial. These results suggest that the WBV session causes secretions of Epi and NE, and it subsequently increases FFA concentration during the recovery period. However, because the FFA response was inconsistent with that of glycerol, we were unable to clarify the effect of WBV exposure on lipolysis.

The impact of metabolic stress on hormonal responses and muscular adaptations.

PURPOSE: The purpose of this study was to examine the impact of exercise-induced metabolic stress on hormonal responses and chronic muscular adaptations. METHODS: We compared the acute and long-term effects of an "NR regimen" (no-rest regimen) and those of a "WR regimen" (regimen with rest period within a set). Twenty-six male subjects were assigned to either the NR (N = 9), WR (N = 9), or control (CON, N = 8) groups. The NR regimen consisted of 3-5 sets of 10 repetitions at 10-repetition maximum (RM) with an interset rest period of 1 min (lat pulldown, shoulder press, and bilateral knee extension). In the WR regimen, subjects completed the same protocol as the NR regimen, but took a 30-s rest period at the midpoint of each set of exercises in order to reduce exercise-induced metabolic stress. Acute hormonal responses to both regimens were measured followed by a 12-wk period of resistance training. RESULTS: Measurements of blood lactate and serum hormone concentrations after the NR and WR regimens showed that the NR regimen induced strong lactate, growth hormone (GH), epinephrine (E), and norepinephrine (NE) responses, whereas the WR regimen did not. Both regimens failed to cause significant changes in testosterone. After 12 wk of resistance training, the NR regimen caused greater increases in 1RM (P < 0.01), maximal isometric strength (P < 0.05), and muscular endurance (P < 0.05) with knee extension than the WR regimen. The NR group showed a marked increase (P < 0.01) in muscle cross-sectional area, whereas the WR and CON groups did not. CONCLUSION: These results suggest that exercise-induced metabolic stress is associated with acute GH, E, and NE responses and chronic muscular adaptations following resistance training.

Prior endurance exercise attenuates growth hormone response to subsequent resistance exercise.

This study examined the influence of prior endurance exercise on hormonal responses to subsequent resistance exercise. Ten males exercised on a cycle ergometer at 50% of maximal oxygen uptake for 60 min and subsequently completed a resistance exercise (bench and leg press, four sets at ten repetitions maximum with an interset rest period of 90 s). Alternatively, the subjects performed the protocol on a separate day with prior endurance exercise limited to 5 min. Blood was obtained before and after the endurance exercise, and 10, 20, and 30 min after the resistance exercise. Maximal isometric torque measured before and after endurance and resistance exercises showed no significant difference between trials. No significant difference was seen in the concentrations of glucose, lactate, testosterone, and cortisol between the trials, but free fatty acids (FFA) and growth hormone (GH) increased (P<0.01 and P<0.05, respectively) after 60 min of endurance exercise. Conversely, after the resistance exercise, GH was attenuated by 60 min of prior exercise (P<0.05). These results indicate that the GH response to resistance exercise is attenuated by prior endurance exercise. This effect might be caused by the increase in blood FFA concentration at the beginning of resistance exercise.

Muscular adaptations to combinations of high- and low-intensity resistance exercises.

Acute and long-term effects of resistance-training regimens with varied combinations of high- and low-intensity exercises were studied. Acute changes in the serum growth hormone (GH) concentration were initially measured after 3 types of regimens for knee extension exercise: a medium intensity (approximately 10 repetition maximum [RM]) short interset rest period (30 s) with progressively decreasing load ("hypertrophy type"); 5 sets of a high-intensity (90% of 1RM) and low-repetition exercise ("strength type"); and a single set of low-intensity and high-repetition exercise added immediately after the strength-type regimen ("combi-type"). Postexercise increases in serum GH concentration showed a significant regimen dependence: hypertrophy-type > combi-type > strength-type (p < 0.05, n = 8). Next, the long-term effects of periodized training protocols with the above regimens on muscular function were investigated. Male subjects (n = 16) were assigned to either hypertrophy/combi (HC) or hypertrophy/ strength (HS) groups and performed leg press and extension exercises twice a week for 10 weeks. During the first 6 weeks, both groups used the hypertrophy-type regimen to gain muscular size. During the subsequent 4 weeks, HC and HS groups performed combi-type and strength-type regimens, respectively. Muscular strength, endurance, and cross sectional area (CSA) were examined after 2, 6, and 10 weeks. After the initial 6 weeks, no significant difference was seen in the percentage changes of all variables between the groups. After the subsequent 4 weeks, however, 1RM of leg press, maximal isokinetic strength, and muscular endurance of leg extension showed significantly (p < 0.05) larger increases in the HC group than in the HS group. In addition, increases in CSA after this period also tended to be larger in the HC group than in the HS group (p = 0.08). The results suggest that a combination of high- and low-intensity regimens is effective for optimizing the strength adaptation of muscle in a periodized training program.

High level of skeletal muscle carnosine contributes to the latter half of exercise performance during 30-s maximal cycle ergometer sprinting.

The histidine-containing dipeptide carnosine (beta-alanyl-L-histidine) has been shown to significantly contribute to the physicochemical buffering in skeletal muscles, which maintains acid-base balance when a large quantity of H(+) is produced in association with lactic acid accumulation during high-intensity exercise. The purpose of the present study was to examine the relations among the skeletal muscle carnosine concentration, fiber-type distribution, and high-intensity exercise performance. The subjects were 11 healthy men. Muscle biopsy samples were taken from the vastus lateralis at rest. The carnosine concentration was determined by the use of an amino acid autoanalyzer. The fiber-type distribution was determined by the staining intensity of myosin adenosinetriphosphatase. The high-intensity exercise performance was assessed by the use of 30-s maximal cycle ergometer sprinting. A significant correlation was demonstrated between the carnosine concentration and the type IIX fiber composition (r=0.646, p<0.05). The carnosine concentration was significantly correlated with the mean power per body mass (r=0.785, p<0.01) during the 30-s sprinting. When dividing the sprinting into 6 phases (0-5, 6-10, 11-15, 16-20, 21-25, 26-30 s), significant correlations were observed between the carnosine concentration and the mean power per body mass of the final 2 phases (21-25 s: r=0.694, p<0.05; 26-30 s: r=0.660, p<0.05). These results indicated that the carnosine concentration could be an important factor in determining the high-intensity exercise performance.