Search

Study aim: The purpose of this study was to compare the effects of cold-water immersion (CWI) vs. active recovery performed after each individual strength and endurance training session over a 10-week period of high-intensity combined strength and endurance training.

Purpose: To examine acute responses of force production and oxygen uptake to combined strength (S) and endurance-running (E) loading sessions in which the order of exercises is reversed (ES vs SE). Methods: This crossover study design included recreationally endurance-trained men and women (age 21-45 y; n = 12 men, 10 women) who performed ES and SE loadings. Force production of the lower extremities including countermovement-jump height (CMJ) and maximal isometric strength (MVC) was measured pre-, mid-, and post-ES and -SE, and ground-reaction forces, ground-reaction times, and running economy were measured during E. Results: A significant decrease in CMJ was observed after combined ES and SE in men (4.5% ± 7.0% and 6.6% ± 7.7%, respectively) but not in women (0.2% ± 8.5% and 1.4% ± 7.3% in ES and SE). MVC decreased significantly in both men (20.7% ± 6.1% ES and 19.3% ± 9.4% SE) and women (12.4% ± 9.3% ES and 11.6% ± 12.0% SE). Stride length decreased significantly in ES and SE men, but not in women. No changes were observed in ground-reaction times during running in men or women. Performing S before E caused greater (P < .01) oxygen uptake during running in both men and women than if E was performed before S, although heart rate and blood lactate were similar between ES and SE. Conclusions: Performing S before E increased oxygen uptake during E, which is explained, in part, by a decrease in MVC in both men and women, decreased CMJ and stride length in men, and/or an increase in postexercise oxygen consumption. [ABSTRACT FROM AUTHOR]

Microdialysis allows for a preview into local muscle metabolism and can provide physiological insight that blood measurements cannot. Purpose: To examine the potential differential IGF-I system regulation in interstitial fluid during unilateral stretch shortening cycle exercise. Methods: 10 men (26 ± 7 year) performed unilateral jumping [stretch shortening cycle (SSC) exercise at 50% of optimal jump height] until volitional fatigue on a sled apparatus. Biological sampling took place using a catheter inserted into an antecubital vein (serum), and 100 kDa microdialysis probes inserted into the thigh muscle of each exercise/control leg (dialysate). Serum was drawn before (Pre; −3 h) and after SSC [Post I (+0 h), II (+3 h), or III (+20 h)]; dialysate was sampled for 2 h before (Pre), during/immediately after (Ex), and 3 h into recovery (Rec) following SSC. IGF-I system parameters (free/total IGF-I and IGFBPs 1–6) were measured with immunoassays. Interstitial free IGF-I was estimated from dialysate IGF-I and relative recovery (ethanol) correction. Data were analyzed with repeated measures ANOVA. Results: Serum total IGF-I remained elevated +3 h (Post II: 182.8 ± 37.6 vs. Pre: 168.3 ± 35.0 ng/mL, p < 0.01), but returned to baseline by +20 h (Post III vs. Pre, p = 0.31). No changes in serum free IGF-I were noted. Serum BP-1 and −3 increased over baseline, but not until + 20 h after SSC (Post III vs. Pre: 7.6 ± 4.9 vs. 3.7 ± 2.3 and 1,048.6 ± 269.2 vs. 891.4 ± 171.2 ng/mL, respectively). We observed a decreased serum BP-6 +3 h after SSC (p < 0.01), followed by a return to baseline at +20 h (p = 0.64 vs. Pre). There were no exercise-induced changes in serum BP-2, −4, or −5. Unlike serum, there were no changes in dialysate or interstitial free IGF-I in either leg (p > 0.05). Dialysate BP-1 remained increased in both exercise and control legs through 3 h into recovery (Rec vs. Pre, p < 0.01). Dialysate BP-3 also demonstrated a prolonged elevation over Pre SSC concentrations, but in the exercise leg only (Ex and Rec vs. Pre, p < 0.04). We observed a prolonged decrease in dialysate BP-5 (Ex and Rec vs. Pre, p < 0.03) and an increase in BP-4 IP in the exercise leg only. There were no changes relative to Pre SSC in dialysate BP-2 or −6. Conclusions : Unilateral exercise drives differential regulation of the IGF-I system at both local and systemic levels. More specifically, this is the first study to demonstrate that localized exercise increases IGFBP-3, IGFBP-4 and decreases in IGFBP-5 in muscle interstitial fluid. [ABSTRACT FROM AUTHOR]

The authors discuss issues on women in sport science and sex differences in responses and adaptations to training. Topics mentioned include the 18th FINA World Championships in South Korea in July 2019, the performance difference between the world's best male and female athletes across a range of sports, and the ability of women to legally and ethically alter their hormonal profile and menstrual cycle through exogenous hormones.

Copyright of Applied Physiology, Nutrition & Metabolism is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The primary aim of the present study was to investigate the acute gene expression responses of PGC-1 isoforms and PGC-1α target genes related to mitochondrial biogenesis ( cytochrome C), angiogenesis ( VEGF-A), and muscle hypertrophy (myostatin), after a resistance or endurance exercise bout. In addition, the study aimed to elucidate whether the expression changes of studied transcripts were linked to phosphorylation of AMPK and MAPK p38. Nineteen physically active men were divided into resistance exercise ( RE, n = 11) and endurance exercise ( EE, n = 8) groups. RE group performed leg press exercise (10 × 10 RM, 50 min) and EE walked on a treadmill (~80% HRmax, 50 min). Muscle biopsies were obtained from the vastus lateralis muscle before, 30 min, and 180 min after exercise. EE and RE significantly increased the gene expression of alternative promoter originated PGC-1α exon 1b- and 1bxs'-derived isoforms, whereas the proximal promoter originated exon 1a-derived transcripts were less inducible and were upregulated only after EE. Truncated PGC-1α transcripts were upregulated both after EE and RE. Neither RE nor EE affected the expression of PGC-1β. EE upregulated the expression of cytochrome C and VEGF-A, whereas RE upregulated VEGF-A and downregulated myostatin. Both EE and RE increased the levels of p- AMPK and p- MAPK p38, but these changes were not linked to the gene expression responses of PGC-1 isoforms. The present study comprehensively assayed PGC-1 transcripts in human skeletal muscle and showed exercise mode-specific responses thus improving the understanding of early signaling events in exercise-induced muscle adaptations. [ABSTRACT FROM AUTHOR]

The study examined the acute neuromuscular and metabolic responses and recovery (24 and 48 h) to combined strength and endurance sessions (SEs). Recreationally endurance trained men (n= 12) and women (n= 10) performed: endurance running followed immediately by a strength loading (combined endurance and strength session (ES)) and the reverse order (SE). Maximal strength (MVC), countermovement jump height (CMJ), and creatine kinase activity were measured pre-, mid-, post-loading and at 24 and 48 h of recovery. MVC and CMJ were decreased (P< 0.05) at post-ES and SE sessions in men. Only MVC decreased in ES and SE women (P< 0.05). During recovery, no order differences in MVC were observed between sessions in men, but MVC and CMJ remained decreased. During recovery in women, a delayed decrease in CMJ was observed in ES but not in SE (P< 0.01), while MVC returned to baseline at 24 h. Creatine kinase increased (P< 0.05) during both ES and SE and peaked in all groups at 24 h. The present combined ES and SE sessions induced greater neuromuscular fatigue at post in men than in women. The delayed fatigue response in ES women may be an order effect related to muscle damage. [ABSTRACT FROM AUTHOR]

The article reports on research which was conducted to evaluate an eight week supervised, periodized mixed maximal and explosive strength training program which was added to endurance training in recreational endurance runners and was preceded by an eight week preparatory strength training period. Researchers evaluated the program with 34 subjects. They found that mixed strength training combined with endurance training may be more effective than circuit training in recreational endurance runners to benefit their overall fitness.

Purpose: To examine the potential sex differences in adaptations to combined endurance and strength training in recreationally endurance trained (eumenorrheic) women ( n = 9) and men ( n = 10). Methods: Isometric (ISOM max ) and dynamic bilateral leg press (1RM), countermovement jump (CMJ), running performance (3,000 m time trial), lean mass and body fat % (LEAN and FAT% determined by dual X-ray absorptiometry) as well as serum testosterone and cortisol (TES and COR, respectively, measured using hormone-specific immunoassay kits) were examined before a control period and pre, mid, and post a supervised 10-week combined high-intensity interval endurance training (4 × 4 min intervals and 3 × 3 × 100 m repeated sprints) and mixed maximal and explosive strength training. No more than 2 weeks separated training and testing for either women or men and all women were tested in the early follicular phase of the menstrual cycle to minimize the possible influence of menstrual cycle phase on performance measures. Results: Absolute and relative changes in 1RM, CMJ, 3,000 m, LEAN, and FAT% were similar between groups. The only statistically significant differences observed between groups were observed at post and included a larger Δ% increase in ISOM max force in men and a relatively greater Δ% decrease in serum TES in women. Conclusion: Women and men can achieve similar relative adaptations in dynamic maximal strength and CMJ as well as endurance performance gains and body composition over the same high-intensity 10-week combined program, although relative adaptations in TES may differ., (Copyright © 2020 Taipale, Forssell, Ihalainen, Kyröläinen and Häkkinen.)

Understanding how a specific exercise changes daily activity patterns is important when designing physical activity interventions. We examined the effects of strength and interval running exercise sessions on daily activity patterns using recordings of quadriceps and hamstring muscle electromyographic (EMG) activity and inactivity. Five male and five female subjects taking part in a 10-week training programme containing both strength and interval running training sessions were measured for daily muscle EMG activities during three days: on a strength day, an interval running day, and a day without exercise. EMG was measured using textile electrodes embedded into sport shorts that were worn 9.1 ± 1.4 hours/day and results are given as % of recording time. During the total measurement time the muscles were inactive 55 ± 26%, 53 ± 30% and 71 ± 12% during strength training day, interval running day, and day without exercise (n.s.). When compared to the day without exercise, the change in muscle inactivity correlated negatively with change in light muscle activity in strength (r = -0.971, p < 0.001) and interval running days (r = -0.965, p < 0.001). While interval running exercise bout induced a more systematic decrease in muscle inactivity time (from 62 ± 15% to 6 ± 6%, p < 0.001), reductions in muscle inactivity in response to strength exercise were highly individual (range 5-70 pp) despite the same training programme. Strength, but not running exercise bout, increased muscle activity levels occurring above 50% MVC ( p < 0.05) when compared to a similar period without exercise. The effect of strength exercise bout on total daily recording time increased the EMG amplitudes across the entire intensity spectrum. While strength and interval running exercise are effective in increasing muscle moderate-to-vigorous activity when compared to a similar period without exercise, it comprises only a small part of the day and does not seem to have a systematic effect neither to reduce nor induce compensatory increase in the daily muscle inactivity that is highly heterogeneous between individuals., Competing Interests: Conflict of Interest: All authors declare no conflicts of interest in this paper.

This study examined acute hormone and force responses and strength and endurance performance and muscle hypertrophy before and after 24 weeks of same-session combined strength and endurance training in previously untrained women. Subjects were assigned 1 of 2 training orders: endurance preceding strength (E + S, n = 15) or vice versa (S + E, n = 14). Acute force and hormone responses to a combined loading (continuous cycling and a leg press protocol in the assigned order) were measured. Additionally, leg press 1 repetition maximum (1RM), maximal workload during cycling (Wmax), and muscle cross-sectional area (CSA) were assessed. Loading-induced decreases in force were significant (p < 0.01-0.001) before (E + S = 20 ± 11%, S + E = 18 ± 5%) and after (E + S = 24 ± 6%, S + E = 22 ± 8%) training. Recovery was completed within 24 hours in both groups. The acute growth hormone (GH) response was significantly (p < 0.001) higher after S + E than E + S at both weeks 0 and 24. Testosterone was significantly (p < 0.001) elevated only after the S + E loading at week 24 but was not significantly different from E + S. Both groups significantly (p < 0.001) improved 1RM (E + S = 13 ± 12%, S + E = 16 ± 10%), Wmax (E + S = 21 ± 10%, S + E = 16 ± 12%), and CSA (E + S = 15 ± 10%, S + E = 11 ± 8%). This study showed that the acute GH response to combined endurance and strength loadings was significantly larger in S + E compared with E + S both before and after 24 weeks of same-session combined training. Strength and endurance performance and CSA increased to similar extents in both groups during 24 weeks despite differences in the kinetics of GH. Previously untrained women can improve performance and increase muscle CSA using either exercise order.

Military operations often induce fatigue resulting from load carriage. Recovery promotes military readiness. This study investigated the acute effects of AR vs. PR after load carriage on maximal isometric leg extension force (MVC) and serum hormonal concentrations. Male reservists (27 ± 3 years, 180 ± 7 cm, 74 ± 11 kg, V[Combining Dot Above]O2max 64 ± 9 ml·kg⁻¹·min⁻¹) completed PR (n = 8) or AR (n = 8) after 50 minutes of loaded (16 kg) uphill (gradient 4.0%) treadmill marching at individual anaerobic threshold. No differences were observed between groups in relative changes in MVC during the marching loading, after AR or PR or the next morning. Significant differences in relative responses to AR and PR postmarching loading were observed in serum testosterone (T), cortisol, and sex-hormone binding globulin immediately post AR and PR; however the next morning, all serum hormone concentrations had returned to normal. This study did not reveal any significant differences between the effects of AR and PR after an hour-long marching protocol at approximately anaerobic threshold on MVC or serum hormones the morning after the experimental marching protocol. Thus, based on the variable measured in this study, marching performed by physically fit army reservists at an intensity at or below anaerobic threshold may not necessitate specialized recovery protocols.

Purpose: To examine acute responses and recovery of serum hormones and muscle force following combined strength (S) and endurance (E) loading sessions in which the order of exercises is reversed (ES vs. SE)., Methods: This cross-over study design included recreationally endurance trained men and women (age 21-45 years, n = 12 men n = 10 women) who performed both loadings. Maximal bilateral isometric strength (MVC), isometric rate of force development (RFD) and serum concentrations of testosterone (T), cortisol (C), growth hormone (GH), insulin-like growth factor 1 (IGF-1), binding protein 3 (IGFBP3) and sex hormone binding globulin (SHBG) were measured during and after both loadings., Results: Both of the present combined (ES and SE) loadings led to a greater acute decrease in MVC in men than in women, while RFD was slightly affected only in men. Recovery of MVC and RFD to baseline was complete at 24 h regardless of the order of exercises. In men, neuromuscular fatigue was accompanied by increased C concentrations observed post SE. This was followed by decreased concentrations of T at 24 h and 48 h that were significantly lower than those observed following ES. GH response in men also differed significantly post loadings. In women, only a significant difference in T between ES and SE loadings was observed at post., Conclusion: These observed differences in hormonal responses despite similarities in neuromuscular fatigue in men indicate the presence of an order effect as the body was not fully recovered at 48 h following SE. These findings may be applicable in training prescription in order to optimize specific training adaptations.