Influence of the Menstrual Cycle on Muscle Glycogen Repletion After Exhaustive Exercise in Eumenorrheic Women.

ABSTRACT: Matsuda, T, Takahashi, H, Nakamura, M, Ogata, H, Kanno, M, Ishikawa, A, and Sakamaki-Sunaga, M. Influence of the menstrual cycle on muscle glycogen repletion after exhaustive exercise in eumenorrheic women. J Strength Cond Res 37(4): e273-e279, 2023-The purpose of this study was to investigate the effect of the menstrual cycle on muscle glycogen repletion postexercise. Eleven women with regular menstrual cycles (age: 20.2 ± 1.3 years, height: 161.1 ± 4.8 cm, and body mass: 55.5 ± 5.7 kg) were assessed in 3 phases of the cycle: the early follicular phase (E-FP), late follicular phase (L-FP), and luteal phase (LP). Each test day began with glycogen-depleting exercise, followed by 5 hours of recovery. Muscle glycogen concentrations, using 13 C-magnetic resonance spectroscopy, and estradiol, progesterone, blood glucose, blood lactate, free fatty acid (FFA), and insulin concentrations were measured at t = 0, 120, and 300 minutes postexercise. During the 5-hour recovery period, subjects consumed 1.2g·(kg body mass) -1 ·h -1 of carbohydrates every 30 minutes. The muscle glycogen concentrations increased at t = 120 and t = 300 minutes postexercise ( p < 0.01) but were not significantly different between the menstrual cycle phases ( p = 0.30). Blood lactate concentrations were significantly higher in the L-FP and LP than in the E-FP ( p < 0.05). Nonetheless, the blood glucose, FFA, insulin concentrations, and the exercise time until exhaustion in the E-FP, L-FP, and LP were similar (blood glucose, p = 0.17; FFA, p = 0.50; insulin, p = 0.31; exercise time, p = 0.67). In conclusion, the menstrual cycle did not influence muscle glycogen repletion after exercise.

The Effect of Co-Ingestion of Carbohydrate with Milk after Exercise in Healthy Women: Study Considering the Menstrual Cycle.

This study aimed to assess the effects of co-ingestion of carbohydrate with milk (MILK) and isocaloric carbohydrate beverage (CHO) on post-exercise recovery and subsequent exercise capacity, considering the menstrual cycle. This study included 12 women with regular menstrual cycles who completed four test days, which started with glycogen-depleting exercise using a cycle ergometer in the early follicular phase (EF) and late follicular phase (LF), followed by 240 min of recovery from the ingestion of 200 mL of CHO or MILK every 30 min immediately after the exercise (POST0) until 210 min post-exercise. After 240 min, participants performed an exercise capacity test. Blood samples and breathing gas samples were collected before the exercise (PRE), POST0, and 120 (POST120) and 240 min after the end of exercise (POST240) to determine the concentrations of estradiol, progesterone, blood glucose, blood lactate, free fatty acid (FFA), and insulin and the respiratory exchange ratio, fat oxidation, and carbohydrate oxidation. The exercise time at exercise capacity test was not significantly different in terms of menstrual cycle phases and recovery beverages ingested. However, there was a significant positive correlation between the exercise capacity test and area under the curve (AUC) of FFA concentrations from POST0 to POST240 in each group (EF + CHO, p < 0.05; LF + CHO, p < 0.05; EF + MILK, p < 0.01; and LF + MILK, p < 0.05). The AUC of FFA from POST120 to POST240 showed no difference between EF (CHO and MILK) and LF (CHO and MILK). However, the AUC of FFA concentrations from POST120 to POST240 was significantly greater in MILK (EF and LF) than that in CHO (EF and LF) (p < 0.05). In active women, circulating substrates and hormone concentrations during short recovery post-exercise are not affected by the menstrual cycle. However, MILK may affect circulating substrates during recovery and the exercise capacity after recovery.

Effect of Green Tea Extract Ingestion on Fat Oxidation during Exercise in the Menstrual Cycle: A Pilot Study.

In women, fat oxidation during exercise changes with the menstrual cycle. This study aimed to investigate the effect of green tea extract (GTE) ingestion on fat oxidation during exercise depending on the menstrual cycle phase. Ten women with regular menstrual cycles participated in this randomized, double-blind, crossover study. GTE or placebo was administered during the menstrual cycle's follicular phase (FP) and luteal phase (LP). Participants cycled for 30 min at 50% maximal workload, and a respiratory gas analysis was performed. Serum estradiol, progesterone, free fatty acid, plasma noradrenaline, blood glucose, and lactate concentrations were assessed before, during, and after the exercise. Fat oxidation, carbohydrate oxidation, and the respiratory exchange ratio (RER) were calculated using respiratory gas. Fat oxidation during the exercise was significantly higher in the FP than in the LP with the placebo (p < 0.05) but did not differ between the phases with GTE. Carbohydrate oxidation, serum-free fatty acid, plasma noradrenaline, blood glucose, and lactate concentrations were not significantly different between the phases in either trial. Our results suggest that GTE ingestion improves the decrease in fat oxidation in the LP.

Influence of menstrual cycle on muscle glycogen utilization during high-intensity intermittent exercise until exhaustion in healthy women.

The present study investigated the effects of the menstrual cycle on muscle glycogen and circulating substrates during high-intensity intermittent exercise until exhaustion in healthy women who habitually exercised. In total, 11 women with regular menstrual cycles completed three tests, which comprised the early follicular phase (E-FP), late follicular phase (L-FP), and luteal phase (LP) of the menstrual cycle. High-intensity intermittent exercise until exhaustion was performed on each test day. Evaluation of muscle glycogen concentration by 13C-magnetic resonance spectroscopy and measurement of estradiol, progesterone, blood glucose, lactate, free fatty acids (FFA), and insulin concentrations were conducted before exercise (Pre) and immediately after exercise (Post). Muscle glycogen concentrations from thigh muscles at Pre and Post were not significantly different between menstrual cycle phases (P = 0.57). Muscle glycogen decreases by exercise were significantly greater in L-FP (59.0 ± 12.4 mM) than in E-FP (48.3 ± 14.4 mM, P < 0.05). Nonetheless, blood glucose, blood lactate, serum FFA, serum insulin concentrations, and exercise time until exhaustion in E-FP, L-FP, and LP were similar. The study results suggest that although exercise time does not change according to the menstrual cycle, the menstrual cycle influences muscle glycogen utilization during high-intensity intermittent exercise until exhaustion in women with habitual exercise activity. Novelty: This study compared changes in muscle glycogen concentration across the menstrual cycle during high-intensity intermittent exercise until exhaustion using 13C-magnetic resonance spectroscopy. Our results highlight the influence of the menstrual cycle on muscle glycogen during high-intensity intermittent exercise in healthy women.

Effects of menstrual cycle on appetite-regulating hormones and energy intake in response to cycling exercise in physically active women.

Although ample evidence supports the notion that an acute bout of endurance exercise performed at or greater than 70% of maximum oxygen uptake suppresses appetite partly through changes in appetite-regulating hormones, no study has directly compared the influence between the phases of the menstrual cycle in women. This study compared the effects of an acute bout of exercise on orexigenic hormone (acylated ghrelin) and anorexigenic hormones (peptide YY and cholecystokinin) between the early follicular phase (FP) and the mid luteal phase (LP) of the menstrual cycle in physically active women. Ten healthy women (age, 20.6 ± 0.7 yr) completed two 3.5-h trials in each menstrual phase. In both trials, participants performed cycling exercises at 70% of heart rate reserve (at a corresponding intensity to 70% of maximum oxygen uptake) for 60 min followed by 90 min of rest. Following 90 min of rest, participants were provided with an ad libitum meal for a fixed duration of 30 min. Blood samples and subjective appetite were collected and assessed before exercise, during exercise, immediately postexercise, 45 min postexercise, and 90 min postexercise. The exercise increased estradiol (327%) and progesterone (681%) in the LP more than the FP, respectively (P < 0.001, f = 1.33; P < 0.001, f = 1.20). There were no between-trial differences in appetite-regulating hormones, subjective appetite, or energy intake of ad libitum meal. These findings indicate that exercise-induced increases in ovarian hormones in the LP may not influence appetite-regulating hormones in physically active women.NEW & NOTEWORTHY To our knowledge, this is the first study to compare how different phases of the menstrual cycle influence appetite-regulating hormones after acute exercise in healthy women. There were no differences in appetite-regulating hormones between the early follicular and mid luteal phases, whereas ovarian hormones were remarkably increased by cycling exercise in the mid luteal phase. These results highlight that appetite-regulating hormones in response to exercise do not appear to be influenced by the menstrual cycle.

Effects of the menstrual cycle on oxidative stress and antioxidant response to high-intensity intermittent exercise until exhaustion in healthy women.

BACKGROUND: This study aimed to investigate the effects of the menstrual cycle on the oxidative stress and antioxidant response during high-intensity intermittent exercise until exhaustion in healthy women who habitually exercised. METHODS: Ten women with normal menstrual cycle completed 2 menstrual cycle phases, including the early follicular phase (FP) and the midluteal phase (LP). High-intensity exercise until exhaustion was performed on each test day. Blood samples were collected before the exercise (Pre), immediately after the exercise (Post0), and 60 minutes after the exercise (Post60). The levels of estradiol; progesterone; oxidative stress, which was measured as diacron reactive oxygen metabolites (d-ROMs); and antioxidant capacity, which was measured as the biological antioxidant potential (BAP), were assessed. RESULTS: The levels of serum estradiol and progesterone at Pre were significantly higher in the LP than in the FP (P<0.01). There were no significant differences in the d-ROMs, BAP, and BAP/d-ROMs between the FP and the LP at Pre, Post0, and Post60. Compared with the FP, the LP had significantly lower d-ROMs change rate from Pre at Post0 and Post60 (P<0.05). Moreover, the BAP/d-ROMs change rate from Pre showed a significantly higher trend in the LP than in the FP at Post0 and Post60 (P=0.06). CONCLUSIONS: In women with regular menstrual cycle, oxidative stress during exercise and recovery may be eliminated during the LP, when the estradiol and progesterone levels are higher, compared with those during the FP.