No effect of menstrual cycle phase on glycerol or palmitate kinetics during 90 min of moderate exercise

Abstract

No effect of menstrual cycle phase on glycerol or palmitate kinetics during 90 min of moderate exercise. J Appl Physiol 100: 917-925, 2006; doi:10.1152/japplphysiol.00491.2005.-The systemic flux of glycerol and palmitate [a representative nonesterified free fatty acid (NEFA)] was assessed in three different phases of the menstrual cycle at rest and during moderate-intensity exercise. It was hypothesized that circulating glycerol and NEFA turnover would be greatest in the midfollicular (MF) phase of the menstrual cycle, when estrogen is elevated but progesterone low, followed by the midluteal phase (ML; high estrogen and progesterone), and lowest in the early follicular (EF) phase of the menstrual cycle (low estrogen and progesterone). Subjects included moderately active, eumenorrheic, healthy women. Testing occurred after 3 days of diet control and after an overnight fast (12-13 h). Resting and exercise (50% maximal oxygen uptake, 90 min) measurements of tracer-determined glycerol and palmitate kinetics were made. There was a significant increase in both glycerol and palmitate turnover from rest to exercise in all phases of the menstrual cycle (P Ͻ 0.0001). No significant differences, however, were observed between cycle phases in the systemic flux of glycerol or palmitate, at rest or during exercise. Maximal peripheral lipolysis during exercise, as represented by glycerol rate of appearance at 90 min, equaled 8.45 Ϯ 0.96, 8.35 Ϯ 1.12, and 7.71 Ϯ 0.96 mol ⅐ kg Ϫ1 ⅐ min Ϫ1 in the EF, MF, and ML phases, respectively. Circulating free fatty acid utilization also peaked at 90 min of exercise, as indicated by the palmitate rate of disappearance (3.31 Ϯ 0.35, 3.17 Ϯ 0.39, and 3.47 Ϯ 0.26 mol ⅐ kg Ϫ1 ⅐ min Ϫ1 ) in the EF, MF, and ML phases, respectively. In conclusion, systemic rates of glycerol and NEFA turnover (as represented by palmitate flux) were not significantly affected by the cyclic fluctuations in estrogen and progesterone that occur throughout the normal menstrual cycle, either at rest or during 90 min of moderate exercise. nonesterified free fatty acid kinetics; lipolysis RECENTLY, THERE HAVE BEEN a number of studies that have addressed the effect of the normal menstrual cycle on whole body substrate oxidation during exercise. This has been of interest both from the perspective of establishing any potential role of the normal variation in estrogen and progesterone on substrate metabolism as well as establishing the necessity to control for sex steroid hormone status in metabolic studies including women. In general, the majority of studies have shown that the normal cyclic fluctuations in estrogen and progesterone observed throughout the menstrual cycle do not affect whole body lipid or carbohydrate oxidation, at rest or during moderate exercise (5, 28, 29, 57); nevertheless, menstrual cycle phase may affect substrate metabolism under certain conditions. For example, lower rates of glucose flux and carbohydrate oxidation have been observed in the midluteal (MF) vs. midfollicular (MF) phase when the demand ...

No effect of menstrual cycle phase on basal very-low-density lipoprotein triglyceride and apolipoprotein B-100 kinetics

“…Our finding that plasma FFA concentration and R a were not different between FP and LP is consistent with previous reports on the effect of menstrual cycle phase on basal, postabsorptive plasma FFA concentration and FFA R a (20,24). It is unlikely that this consistent lack of difference was due to insufficient statistical power of the studies or the variation in sex hormone concentrations within each cycle phase.…”

O2 uptake and muscle deoxygenation kinetics during the transition to moderate-intensity exercise in different phases of the menstrual cycle in young adult females

“…The finding in the present study that the RER was not different in either phase of the menstrual cycle contrasts with studies of more prolonged exercise which report that females preferentially utilize fat as a fuel source during the luteal phase of the menstrual cycle (Bonen et al 1983;Dombovy et al 1987;Hackney et al 1994;Hackney 1999;Zderic et al 2001;, although others report no differences in RER between phases of the menstrual cycle (Braun et al 2000;Horton et al 2002Horton et al , 2006. In the present study, RER was measured during the first 6 min of exercise, whereas in previous studies measurements were made later in exercise (>10 min) where an effect of menstrual cycle phase on substrate utilization has been observed (Braun et al 2000;Zderic et al 2001;.…”

Metabolic actions of insulin in men and women

“…Although data is limited, there is so far no evidence that menstrual cycle phase affects basal postabsorptive FFA kinetics [46–48,97,98] or meal fatty acid disposal [99]. The effect of sex hormones on insulin-mediated suppression of lipolysis has to our knowledge not been studied in vivo in human subjects.…”