Effects of a 10-d Military Field Exercise on Body Composition, Physical Performance, and Muscle Cells in Men and Women.

PURPOSE: This study aimed to investigate the effects of a demanding military field exercise on physical performance, body composition, and muscle cellular outcomes in men and women. METHODS: Ten men (20.5 ± 0.5 yr) and 8 women (21.4 ± 1.4 yr) completed a 10-d field exercise consisting of extensive physical activity with food and sleep restriction. Acquisition of body composition, physical performance, blood, and muscle biopsies samples were done before and 1, 7, and 14 d after the exercise. RESULTS: There were no sex differences in the response to the exercise. Body mass was decreased with 5.6% ± 1.8% and fat mass with 31% ± 11% during the exercise. Both were still reduced after 14 d (2.5% ± 2.3%, P < 0.001, and 12.5% ± 7.7%, P < 0.001, respectively). Isometric leg strength did not change. Peak leg extension torque at 240°·s -1 and counter movement jump height were reduced with 4.6% ± 4.8% ( P = 0.012) and 6.7% ± 6.2% ( P < 0.001), respectively, and was still reduced after 14 d (4.3% ± 4.2%, P = 0.002, and 4.1% ± 4.7%, P = 0.030). No changes occurred in fiber CSA, fiber types, proteins involved in calcium handling, or HSP70. During the exercise, αB-crystallin levels decreased by 14% ± 19% ( P = 0.024) in the cytosolic fraction and staining intensity on muscle sections tended to increase (17% ± 25%, P = 0.076). MuRF1 levels in the cytosolic fraction tended to decrease (19% ± 35%) and increased with 85% ± 105% ( P = 0.003) in the cytoskeletal fraction 1 wk after the exercise. CONCLUSIONS: The field exercise resulted in reduced body mass and physical performance in both sexes. The ability to produce force at high contraction velocities and explosive strength was more affected than isometric strength, but this was not related to any changes in fiber type composition, fiber area, Ca 2+ handling, or fiber type-specific muscle damage.

Effects of High and Low-To-Moderate Intensity Exercise During (Neo-) Adjuvant Chemotherapy on Muscle Cells, Cardiorespiratory Fitness, and Muscle Function in Women With Breast Cancer: Protocol for a Randomized Controlled Trial.

BACKGROUND: (Neo-)adjuvant chemotherapy for breast cancer is effective but has deleterious side effects on muscle tissue, resulting in reduced skeletal muscle mass, muscle function, and cardiorespiratory fitness. Various exercise regimens during cancer treatment have been shown to counteract some of these side effects. However, no study has compared the effect of high-intensity training versus low-to-moderate intensity training on muscle tissue cellular outcomes and physical function in patients with breast cancer during chemotherapy. OBJECTIVE: The aim of this substudy within the Physical Training in Cancer (Phys-Can) consortium is to evaluate and compare the effects of high and low-to-moderate intensity exercise on muscle cellular outcomes, muscle function, and cardiorespiratory fitness in women with breast cancer undergoing (neo-)adjuvant chemotherapy. We further aim to investigate if the effects of chemotherapy including taxanes on muscles will be different from those of taxane-free chemotherapy. METHODS: Eighty women recently diagnosed with breast cancer scheduled to start (neo-)adjuvant chemotherapy will be randomized to a combination of strength and endurance training, either at high intensity or at low-to-moderate intensity. Testing of muscle function and cardiorespiratory fitness and collection of muscle biopsies from the vastus lateralis muscle will be performed before the first cycle of chemotherapy (or after 1 week, when not possible) (T0), halfway through chemotherapy (T1), and after completion of chemotherapy (T2). It is estimated that approximately 50% of the participants will be willing to undergo muscle biopsies. To separate the effect of the treatment itself, a usual care group with no supervised training will also be included, and in this group, testing and collection of muscle biopsies will be performed at T0 and T2 only. RESULTS: This study is funded by Active Against Cancer (Aktiv mot kreft) (May 2013) and the Norwegian Cancer Society (December 2018). Inclusion started in December 2016 and the last participant is expected to be recruited in December 2022. As of June 2022, we enrolled 38 (19 with biopsies) participants to the high-intensity training group, 36 (19 with biopsies) participants to the low-to-moderate intensity training group, and 17 (16 with biopsies) participants to the usual care group. Data analyses will start in fall 2022. The first results are expected to be published in spring 2024. CONCLUSIONS: This study will generate new knowledge about the effects of different training intensities for women with breast cancer during chemotherapy treatment. It will give further insight into how chemotherapy affects the muscle tissue and how physical training at different intensities may counteract the treatment side effects in muscles. The results of this study will inform the development and refinement of exercise programs that are effective and compatible with the multidisciplinary management of breast cancer. TRIAL REGISTRATION: ClinicalTrials.gov NCT05218876; https://tinyurl.com/ysaj9dhm. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/40811.

A Comparison of the Effect of Strength Training on Cycling Performance between Men and Women.

During the last decade numerous review articles have been published on how concurrent strength and endurance training affect cycling performance. However, none of these have reviewed if there are any sex differences in the effects of concurrent training on cycling performance, and most research in this area has been performed with male cyclists. Thus, the aim of the current paper is to review the scientific literature on the effect of concurrent training on cycling performance in male and female cyclists with a special emphasis on potential sex differences. The results indicate that both male and female cyclists experience a similar beneficial effect from concurrent training on cycling performance and its physiological determinants compared to normal endurance training only. Some data indicate that women have a larger effect on cycling economy, but more studies are needed to explore this further. Furthermore, the adaptations to strength training thought to be responsible for the beneficial effects on cycling performance seem to be very similar between men and women. Interestingly, increased muscle cross-sectional area in the main locomotor muscles seems to be an important adaptation for improved performance, and, contrary to popular belief, cyclists should aim for increased muscle cross-sectional area when adding strength training to their normal training. We conclude that both male and female cyclists can improve their cycling performance by adding strength training to their normal training.

Effects of heavy-load resistance training during (neo-)adjuvant chemotherapy on muscle cellular outcomes in women with breast cancer.

INTRODUCTION: (Neo-)adjuvant chemotherapy for breast cancer has a deleterious impact on muscle tissue resulting in reduced cardiorespiratory fitness, skeletal muscle mass and function. Physical exercise during treatment may counteract some of these negative effects. However, the effects of resistance training (RT) alone have never been explored. The present study aims to investigate if heavy-load RT during (neo-)adjuvant chemotherapy counteracts deleterious effects on skeletal muscle in women diagnosed with breast cancer. We hypothesize that (neo-)adjuvant treatment with chemotherapy will reduce muscle fiber size, impair mitochondrial function, and increase indicators of cellular stress and that RT during treatment will counteract these negative effects. We also hypothesize that RT during (neo-)adjuvant chemotherapy will increase muscle and blood levels of potential antitumor myokines and reduce treatment-related side effects on muscle strength and cardiorespiratory fitness. METHODS: Fifty women recently diagnosed with breast cancer scheduled to start (neo-)adjuvant chemotherapy will be randomized to either randomized to either intervention group or to control group.The intervention group will perform supervised heavy-load RT twice a week over the course of chemotherapy (approximately 16-weeks) whereas the control group will be encouraged to continue with their usual activities. Muscle biopsies from m. vastus lateralis will be collected before the first cycle of chemotherapy (T0), after chemotherapy (T1), and 6 months later (T2) for assessment of muscle cellular outcomes. The primary outcome for this study is muscle fiber size. Secondary outcomes are: regulators of muscle fiber size and function, indicators of cellular stress and mitochondrial function, myokines with potential antitumor effects, muscle strength, and cardiorespiratory fitness. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the Regional Ethical Review Board in Uppsala, Sweden (Dnr:2016/230/2). Results will be disseminated through presentations at scientific meetings, publications in peer-reviewed journals, social media, and patient organizations. TRIAL REGISTRATION NUMBER: NCT04586517.

Adaptations to strength training differ between endurance-trained and untrained women.

PURPOSE: The purpose of this study was to investigate if endurance athletes, sustaining their normal endurance training, experience attenuated adaptations to strength training compared to untrained individuals. METHODS: Eleven non-strength-trained female endurance athletes (E + S) added 11 weeks of strength training to their normal endurance training (5.1 ± 1.1 h per week), and 10 untrained women (S) performed the same strength training without any endurance training. The strength training consisted of four leg exercises [3 × 4 - 10 repetition maximum (RM)], performed twice a week for 11 weeks. RESULTS: E + S and S displayed similar increases in 1RM one-legged leg press (E + S 39 ± 19%, S 42 ± 17%, p < 0.05), maximal isometric torque in knee extension (E + S 12 ± 11%, S 8 ± 10%, p < 0.05) and lean mass in the legs (E + S 3 ± 4%, S 3 ± 3%, p < 0.05). However, S displayed superior increases in peak torque in knee extension at an angular velocity of 240° sec-1 (E + S 8 ± 5%, S 15 ± 7%, p < 0.05) and maximal squat jump height (E + S 8 ± 6%, S 14 ± 7%, p < 0.05). CONCLUSIONS: In this study, concurrent training did not impair the adaptations in the ability to develop force at low contraction velocities or muscle hypertrophy. However, concurrent training attenuated strength training-associated changes in the ability to develop force at higher muscular contraction velocities.

Sex differences in the physiological response to a demanding military field exercise.

PURPOSE: To investigate sex differences in the effect of a military field exercise on physical performance, body composition, and blood biomarkers. METHODS: Measurements were done in 23 male and 12 female conscripts before, and 0, 1, 3, 7, and 14 days after a 6-day military field exercise. RESULTS: During the field exercise, body mass decreased more in men (-6.5 ± 1.1 kg) than in women (-2.7 ± 0.7 kg), and muscle mass decreased only in men (-2.7 ± 1.0 kg). Body composition recovered within one week. Performance decreased, with no differences between men and women for countermovement jump (CMJ,-19 ± 8 vs. -18 ± 11%), medicine ball throw (MBT, -11 ± 7 vs. -11 ± 7%), and an anaerobic performance test (EVAC, -55 ± 22 vs. -47 ± 31%, men and women, respectively). MBT and EVAC performance recovered within two weeks, whereas CMJ performance was still reduced in men (-17 ± 6%) and women (-9 ± 8%) after two weeks recovery, with a larger reduction in men. Both men and women decreased [IGF-1] (-28 ± 9 vs. -41 ± 8%) and increased [cortisol] (26 ± 26 vs. 66 ± 93%, men and women, respectively) during the exercise. Most biomarkers returned to baseline values within one week. CONCLUSIONS: Men lost more body mass and muscle mass than women during a field exercise, but these differences did not lead to sex differences in changes in explosive strength and anaerobic performance. However, women recovered explosive strength in the legs faster than men.

A 11-day compressed overload and taper induces larger physiological improvements than a normal taper in elite cyclists.

Endurance athletes usually achieve performance peaking with 2-4 weeks of overload training followed by 1-3 weeks of tapering. With a tight competition schedule, this may not be appropriate. Thus, the aim of this study was to compare the effect of a compressed variant of the recommended overload and tapering approach (EXP; n = 9, VO2peak  = 77 ± 5 mL·min-1 ·kg-1 ) with a 11-day traditional taper that maintained the usual frequency of high-intensity aerobic interval training (HIT) and reduced the duration of training at lower exercise intensity (TRAD, n = 8, VO2peak  = 74 ± 4 mL·min-1 ·kg-1 ) on physiological and psychological variables of endurance performance. EXP performed a 6-day period with daily HIT followed by a 5-day step taper. Testing was performed before the intervention (pre), on the 7th (post-1), and on the 11th day of the intervention (post-2). From pre to post-2, EXP achieved a larger relative improvement than TRAD in VO2peak (4.0 ± 3.7% vs 0.8 ± 1.8%, respectively, P = .041) and the 1-min peak power output from the VO2peak test (5.0 ± 3.6% vs 0.9 ± 1.5%, respectively, P = .009) and had a tendency toward larger improvement in power output at a blood lactate concentration of 4 mmol∙L-1 (P = .088) and peak isokinetic knee extension (P = .06). The effect size of the relative improvement in the endurance variables revealed a moderate-to-large effect of EXP vs TRAD. In conclusion, this study indicates that elite cyclists performing the present 11-day compressed performance peaking protocol consisting of a 6-day HIT overload followed by a 5-day step taper are superior to a 11-day taper only.

Heavy strength training improves running and cycling performance following prolonged submaximal work in well-trained female athletes.

The purpose of this study was to investigate the effects of adding heavy strength training to female duathletes' normal endurance training on both cycling and running performance. Nineteen well-trained female duathletes (VO2max cycling: 54 ± 3 ml∙kg-1∙min-1, VO2max running: 53 ± 3 ml∙kg-1∙min-1) were randomly assigned to either normal endurance training (E, n = 8) or normal endurance training combined with strength training (E+S, n = 11). The strength training consisted of four lower body exercises [3 × 4-10 repetition maximum (RM)] twice a week for 11 weeks. Running and cycling performance were assessed using 5-min all-out tests, performed immediately after prolonged periods of submaximal work (3 h cycling or 1.5 h running). E+S increased 1RM in half squat (45 ± 22%) and lean mass in the legs (3.1 ± 4.0%) more than E Performance during the 5-min all-out test increased in both cycling (7.0 ± 4.5%) and running (4.7 ± 6.0%) in E+S, whereas no changes occurred in E The changes in running performance were different between groups. E+S reduced oxygen consumption and heart rate during the final 2 h of prolonged cycling, whereas no changes occurred in E No changes occurred during the prolonged running in any group. Adding strength training to normal endurance training in well-trained female duathletes improved both running and cycling performance when tested immediately after prolonged submaximal work.

Effects of Heavy Strength Training on Running Performance and Determinants of Running Performance in Female Endurance Athletes.

PURPOSE: The purpose of the current study was to investigate the effects of adding strength training to normal endurance training on running performance and running economy in well-trained female athletes. We hypothesized that the added strength training would improve performance and running economy through altered stiffness of the muscle-tendon complex of leg extensors. METHODS: Nineteen female endurance athletes [maximal oxygen consumption (VO2max): 53±3 ml∙kg-1∙min-1, 5.8 h weekly endurance training] were randomly assigned to either normal endurance training (E, n = 8) or normal endurance training combined with strength training (E+S, n = 11). The strength training consisted of four leg exercises [3 x 4-10 repetition maximum (RM)], twice a week for 11 weeks. Muscle strength, 40 min all-out running distance, running performance determinants and patellar tendon stiffness were measured before and after the intervention. RESULTS: E+S increased 1RM in leg exercises (40 ± 15%) and maximal jumping height in counter movement jump (6 ± 6%) and squat jump (9 ± 7%, p < 0.05). This was accompanied by increased muscle fiber cross sectional area of both fiber type I (13 ± 7%) and fiber type II (31 ± 20%) in m. vastus lateralis (p < 0.05), with no change in capillary density in m. vastus lateralis or the stiffness of the patellar tendon. Neither E+S nor E changed running economy, fractional utilization of VO2max or VO2max. There were also no change in running distance during a 40 min all-out running test in neither of the groups. CONCLUSION: Adding heavy strength training to endurance training did not affect 40 min all-out running performance or running economy compared to endurance training only.