Endurance training and menstrual cycle : effects of menstrual cycle based-training on physiologic measures of endurance capacity and on muscle cell parameters on women with and without oral contraception
|Title translated into German:||Ausdauertraining und Menstruationszyklus : Auswirkungen des auf den Menstruationszyklus abgestimmtenTrainings auf physiologische Maßnahmen der Ausdauerleistungsfähigkeit und auf die Muskelzellparameter bei Frauen mit und ohne oraler Kontrazeption|
|Published:||Bochum: 2012, XI, 74 S., Lit.|
|Research institution:||Universität Bochum / Fakultät für Sportwissenschaft|
|Notes:||Univ., Bochum, Diss., 2012|
|Format:||Publications (Database SPOLIT)|
|Media type:||Electronic resource (online) Print resource|
|Document Type:||Doctoral thesis Grey literature|
Purpose: The menstrual cycle shows fluctuations in various endogenous hormones between the follicular and the luteal phase in women, who do not take oral contraceptives (OC). With the intake of OC biosynthesis and secretion of the endogenous hormones estrogen and progesterone are suppressed and other sex steroids are altered in different ways. Variations of these hormonal milieus might influence trainability of endurance performance differently either between the menstrual cycle phases or between women with oral contraceptives and women without oral contraceptives. Therefore, this thesis aimed to investigate hormone profiles during the menstrual cycle and the effects of menstrual cycle phase-based endurance training on physiologic and microscopic measures of aerobic capacity in eumenorrheic women, who do not take any oral contraceptive (non- OC users) and in women, who take a combined monophasic oral contraceptive (OC users). Study 1 investigated follicular phase-based (FT) vs. luteal phase-based (LT) endurance training in non-OC users. Study 2 investigated quasi-follicular phase-based (qFT) vs. quasi-luteal phase-based (qLT) endurance training in monophasic OC users.
Study 3 compared hormonal profiles and parameters of endurance performance from both studies between non-OC users and OC users.
METHODS: Thirteen non-OC users and fourteen OC users completed one-leg endurance training on a cycle ergometer for three menstrual cycles. One leg was trained mainly in the first half of the menstrual cycle (follicular phase training (FT) and quasi-follicular phase training (qFT), respectively) and the other leg mainly in the second half of the cycle (luteal phase training (LT) and quasi-luteal phase training (qLT), respectively). Venous blood samples were taken on day 11 of the menstrual cycle in the follicular phase (FP) / quasi-follicular phase (qFP) and on day 25 of the menstrual cycle in the luteal phase (LP) / quasi-luteal phase (qLP) to analyze values of 17-beta estradiol (E2), progesterone (P4), total testosterone (T), free testosterone (free T) and DHEA-s. Peak oxygen uptake (V02peak). maximal workload (Wattmax) and power output at a lactate concentration of 4mmol/l (Wattiac4) were analyzed before and after training intervention as well as muscle fiber composition (number of type I and type II fibers), fiber diameter (Fdm) and cell nuclei to fiber ratio (N/F) in subgroups of five and three subjects, respectively. Results: Study 1: Prior to training, concentration of free T was higher in FP compared to LP (P < 0.05). VO2peak increased after FT (P = 0.033) and after LT (P = 0.038) without any difference between FT and LT. Wattmax also increased significantly after both FT and LT. Moreover, we found a noticeably higher increase (P = 0.038) of Wattmax after FT (+ 34.8 W) compared to LT (+ 27.8 W) There seemed to be a slight higher increase in type I Fdm compared to type II Fdm with a slightly more pronounced increase in type I Fdm after FT compared to LT. Study 2: DHEA-s was higher (p < 0 05) in qFP compared to qLP. E2, T and P4 were not significantly different between two phases. V02max and Wattmax increased significantly after qFT and qLT without any difference between both training periodizations. Mdm did not change after qFT and qLT. Number of type I fibers decreased after qFT whereas number of type I fibers increased after qLT. No relevant changes were found in N/F and in Fdm of type I and type II fibers neither after qFT nor after qLT. Study 3: Concentration of E2, T and free T were significantly higher in non-OC users compared to OC users (p<0.05). P4 level was highest in LP compared to all other phases (p<0.05). Absolute increase of Wattmax was the lowest after LT in non-OC users (+ 27.8 W) compared to FT (+ 34.8 W), qFT (+ 32.3 W) and qLT (+ 35.9 W) in OC users. V02peak tended to increase after FT (+3.3 ml/min/kg, P = 0.033) and LT (+2.8 ml/min/kg, P = 0.038) and increased significantly after qFT (+5.7 ml/min/kg) and qLT (+5.3 ml/min/kg) without any differences between non-OC and OC-users. Conclusions: In non-OC users, FT showed a slight and delayed higher effect on maximum power output on a bicycle ergometer compared to LT without any different effect on V02peak and muscle diameter. This might be due to the specific hormonal milieu during each phase of the cycle. In OC-users, however, no differences were found between the two training interventions qFT and qLT. This is presumably due to the constant doses of estrogen and progestin in monophasic OC. As a result, OC users had a more stable hormonal milieu for training adaptation processes at least during the consumption phase of 21 days, resulting in comparable trainability of endurance performance throughout the cycle. Further studies with longer lasting training periods are needed in order to analyze if the late response in aerobic training adaptation becomes more pronounced after more than three months of menstrual cycle-based training in non-OC users. As no menstrual cycle-specific training responses have been observed, we recommend that untrained and moderately trained OC users perform their endurance training independently from their pill cycle. Further studies are necessary in order to understand possible effects of androgenicity of OC pills on development of endurance performance. Furthermore, more subjects have to be included in muscle biopsy analyses in order to understand possible underlying mechanisms of cycle-dependent aerobic training adaptations. Verf.-Referat