Comparison of the cytokine responses to acute strength exercise between oral contraceptive users and naturally cycling women.

PURPOSE: Cytokines are released as part of an inflammatory reaction in response to strength exercise to initiate muscle repair and morphological adaptations. Whether hormonal fluctuations induced by the menstrual cycle or oral contraceptives affect inflammatory responses to strength exercise remains unknown. Therefore, we aimed to compare the response of cytokines after acute strength exercise in naturally menstruating women and oral contraceptive users. METHODS: Naturally menstruating women (MC, n = 13, 24 ± 4 years, weekly strength training: 4.3 ± 1.7 h) and women using a monophasic combined pill (> 9 months) (OC, n = 8, 22 ± 3 years, weekly strength training: 4.5 ± 1.9 h) were recruited. A one-repetition-maximum (1RM) test and strength exercise in the squat (4 × 10 repetitions, 70%1RM) was performed in the early follicular phase or pill free interval. Concentrations of oestradiol, IL-1ß, IL-1ra, IL-6, IL-8, and IL-10 were assessed before (pre), directly after (post) and 24 h after (post24) strength exercise. RESULTS: IL-1ra increased from pre to post (+ 51.1 ± 59.4%, p = 0.189) and statistically decreased from post to post24 (- 20.5 ± 13.5%, p = 0.011) only in OC. Additionally, IL-1ß statistically decreased from post to post24 (- 39.6 ± 23.0%, p = 0.044) only in OC. There was an interaction effect for IL-1ß (p = 0.038) and concentrations were statistically decreased at post24 in OC compared to MC (p = 0.05). IL-8 increased across both groups from post to post24 (+ 66.6 ± 96.3%, p = 0.004). CONCLUSION: We showed a differential regulation of IL-1ß and IL-1ra between OC users in the pill-free interval and naturally cycling women 24 h after strength exercise, while there was no effect on other cytokines. Whether this is associated with previously shown compromised morphological adaptations remains to be investigated.

The repeated bout effect of traditional resistance training on cycling efficiency and performance.

PURPOSE: This study examined the repeated bout effect of two resistance training bouts on cycling efficiency and performance. METHODS: Ten male resistance-untrained cyclists (age 38 ± 13 years; height 180.4 ± 7.0 cm; weight 80.1 ± 10.1; kg; VO2max 51.0 ± 7.6 ml.kg-1.min-1) undertook two resistance training bouts at six-repetition maximum. Blood creatine kinase (CK), delayed-onset of muscle soreness (DOMS), counter-movement jump (CMJ), squat jump (SJ), submaximal cycling and time-trial performance were examined prior to (Tbase), 24 (T24) and 48 (T48) h post each resistance training bout. RESULTS: There were significantly lower values for DOMS (p = 0.027) after Bout 2 than Bout 1. No differences were found between bouts for CK, CMJ, SJ and submaximal cycling performance. However, jump height (CMJ and SJ) submaximal cycling measures (ventilation and perceived exertion) were impaired at T24 and T48 compared to Tbase (p < 0.05). Net efficiency during submaximal cycling improved at Bout 2 (23.8 ± 1.2) than Bout 1 (24.3 ± 1.0%). There were no changes in cycling time-trial performance, although segmental differences in cadence were observed between bouts and time (i.e. Tbase vs T24 vs T48; p < 0.05). CONCLUSION: Cyclists improved their cycling efficiency from Bout 1 to Bout 2 possibly due to the repeated bout effect. However, cyclists maintained their cycling completion times during exercise-induced muscle damage (EIMD) in both resistance training bouts, possibly by altering their cycling strategies. Thus, cyclists should consider EIMD symptomatology after resistance training bouts, particularly for cycling-specific technical sessions, regardless of the repeated bout effect.

Feasibility of a physical exercise intervention for patients on a palliative care unit: a critical analysis.

BACKGROUND: Recent exercise intervention studies have shown promising results in improving quality of life (QoL) and physical function (PF) in diverse chronic disease and advanced cancer patients. However, the effects of structured exercise in palliative care patients, having different therapeutic needs, lower life expectancies and PFs remain unknown. This study primarily aimed to assess the feasibility of an exercise intervention with follow-up by analysing recruitment numbers, screening procedures, acceptability, preferences, and safety of the exercise intervention as well as retention in follow-up. Our secondary aims related to changes in QoL and PF. METHODS: This study comprised of a one-arm design without a control group. Over 6 months, every in-hospital palliative care unit (PCU) patient was screened for eligibility. Eligible patients were asked to participate in a 2-week exercise intervention consisting of resistance training and/or endurance training with moderate or high intensity based on personal preferences and a 4-week follow-up. Before and after the exercise intervention, QoL and PF were assessed and a qualitative interview after the intervention addressed expectations and experiences of the exercise intervention. For follow-up, patients were provided with information on independent training and after 1 and 4 weeks a QoL assessment and qualitative interview were conducted. RESULTS: Of 124 patients screened, 10 completed the intervention with an adherence rate of (80 ± 25%), of which 6 patients completed follow-up. Endurance training was the most performed training type and only a few minor adverse events occurred in certain or likely connection to the exercise intervention. While physical QoL and PF measured by arm curl strength and time up and go performance improved, mental QoL and the other PF tests remained unchanged. CONCLUSION: Despite the challenges that were faced in our screening and testing process, that are specific to the palliative patient population with their unique therapeutic requirements and varying mental-/ physical capabilities, we discovered the 2-week exercise intervention to be feasible, safe, and well tolerated by palliative care patients. Moreover, it seems that short-term improvements in QoL and PF are possible. Further full scale studies are required to confirm our findings. TRIAL REGISTRATION: The study was retrospectively registered on 25.01.2022 in the German Clinical Trials Register (DRKS00027861).

The Impact of Exercise-Induced Muscle Damage on Various Cycling Performance Metrics: A Systematic Review and Meta-Analysis.

ABSTRACT: Devantier-Thomas, B, Deakin, GB, Crowther, F, Schumann, M, and Doma, K. The impact of exercise-induced muscle damage on various cycling performance metrics: a systematic review and meta-analysis. J Strength Cond Res 38(1): 196-212, 2024-This systematic review and meta-analysis examined the impact of exercise-induced muscle damage (EIMD) on cycling performance. The primary outcome measure was cycling performance, whereas secondary outcome measures included creatine kinase (CK), delayed-onset muscle soreness (DOMS), and muscular contractions. Data were extracted and quantified through forest plots to report on the standardized mean difference and p values. The meta-analysis showed no significant change in oxygen consumption at 24-48 hours (p > 0.05) after the muscle damage protocol, although ventilation and rating of perceived exertion significantly increased (p < 0.05) during submaximal cycling protocols. Peak power output during both sprint and incremental cycling performance was significantly reduced (p < 0.05), but time-trial and distance-trial performance showed no change (p > 0.05). Measures of CK and DOMS were significantly increased (p < 0.05), whereas muscular force was significantly reduced following the muscle-damaging protocols (p < 0.05), confirming that cycling performance was assessed during periods of EIMD. This systematic review showed that EIMD affected both maximal and submaximal cycling performance. Therefore, coaches should consider the effect of EIMD on cycling performance when implementing unaccustomed exercise into a cycling program. Careful consideration should be taken to ensure that additional training does not impair performance and endurance adaptation.

Evaluation of the Vmaxpro sensor for assessing movement velocity and load-velocity variables: accuracy and implications for practical use.

We investigated the ecological validity of an inertial measurement unit (IMU) (Vmaxpro) to assess the movement velocity (MV) during a 1-repetition maximum (1RM) test and for the prediction of load-velocity (L-V) variables, as well as the ecological intra- day and inter-day reliability during free-weight bench press (BP) and squat (SQ). Furthermore, we provide recommendations for the practical use of the sensor. Twenty-three strength-trained men completed an incremental 1RM test, whereas seventeen men further participated in another 3 sessions consisting of 3 repetitions with 4 different loads (30, 50, 70 and 90% of 1RM) to assess validity and intra- and inter-day reliability, respectively. The MV was assessed using the Vmaxpro and a 3D motion capture system (MoCap). L-V variables and the 1RM were calculated based on submaximal velocities. The Vmaxpro showed high validity during the 1RM test for BP (r = 0.935) and SQ (r = 0.900), but with decreasing validity at lower MVs. The L-V variables and the 1RM demonstrated high validity for BP (r = 0.808-0.942) and SQ (r = 0.615-0.741) with a systematic overestimation. Coefficients of variance for intra- and inter-day reliability ranged from 2.4% to 9.7% and from 3.2% to 8.6% for BP and SQ, respectively. The Vmaxpro appears valid at high and moderately valid at low MVs. Depending on the required degree of accuracy, the sensor may be sufficient for the prediction of L-V variables and the 1RM. Our data indicate the sensor to be suitable for monitoring changes in MVs within and between training sessions.

Validity and Test-Retest Reliability of the Vmaxpro Sensor for Evaluation of Movement Velocity in the Deep Squat.

ABSTRACT: Feuerbacher, JF, Jacobs, MW, Dragutinovic, B, Goldmann, J-P, Cheng, S, and Schumann, M. Validity and test-retest reliability of the Vmaxpro sensor for evaluation of movement velocity in the deep squat. J Strength Cond Res 37(1): 35-40, 2023-We aimed at assessing the validity and test-retest reliability of the inertial measurement unit-based Vmaxpro sensor compared with a Vicon 3D motion capture system and the T-Force sensor during an incremental 1-repetition maximum (1RM) test and at submaximal loads. Nineteen subjects reported to the laboratory for the 1RM test sessions, whereas 15 subjects carried out another 3 sessions consisting of 3 repetitions with 4 different intensities (30, 50, 70, and 90% of 1RM) to determine the intra- and interday reliability. The Vmaxpro sensor showed high validity (Vicon: R2 = 0.935; T-Force: R2 = 0.968) but an overestimation of the mean velocities (MVs) of 0.06 ± 0.08 m·s-1 and 0.06 ± 0.06 m·s-1 compared with Vicon and T-Force, respectively. Regression analysis indicated a systematic bias that is increasing with higher MVs. The intraclass correlation coefficients (ICCs) for Vmaxpro were moderate to high for intraday (ICC: 0.662-0.938; p ≤ 0.05) and for interday (ICC: 0.568-0.837; p ≤ 0.05) reliability, respectively. The Vmaxpro is a valid and reliable measurement device that can be used to monitor movement velocities within a training session. However, practitioners should be cautious when assessing movement velocities on separate days because of the moderate interday reliability.

Effects of short sprint interval training on aerobic and anaerobic indices: A systematic review and meta-analysis.

The effects of short sprint interval training (sSIT) with efforts of ≤10 s on maximal oxygen consumption (V̇O2 max), aerobic and anaerobic performances remain unknown. To verify the effectiveness of sSIT in physically active adults and athletes, a systematic literature search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The databases PubMed/MEDLINE, ISI Web of Science, and SPORTDiscus were systematically searched on May 9, 2020, and updated on September 14, 2021. Inclusion criteria were based on PICO and included healthy athletes and active adults of any sex (≤40 years), performing supervised sSIT (≤10 s of "all-out" and non-"all-out" efforts) of at least 2 weeks, with a minimum of 6 sessions. As a comparator, a non-sSIT control group, another high-intensity interval training (HIIT) group, or a continuous training (CT) group were required. A total of 18 studies were deemed eligible. The estimated SMDs based on the random-effects model were -0.56 (95% CI: -0.79, -0.33, p < 0.001) for V̇O2 max, -0.43 (95% CI: -0.67, -0.20, p < 0.001) for aerobic performance, and -0.44 (95% CI: -0.70, -0.18, p < 0.001) for anaerobic performance after sSIT vs. no exercise/usual training. However, there were no significant differences (p > 0.05) for all outcomes when comparing sSIT vs. HIIT/CT. Our findings indicate a very high effectiveness of sSIT protocols in different exercise modes (e.g., cycling, running, paddling, and punching) to improve V̇O2 max, aerobic, and anaerobic performances in physically active young healthy adults and athletes.

Acute Effects of High-Intensity Interval Running on Lower-Body and Upper-Body Explosive Strength and Throwing Velocity in Handball Players.

ABSTRACT: Seipp, D, Feuerbacher, JF, Jacobs, MW, Dragutinovic, B, and Schumann, M. Acute effects of high-intensity interval running on lower-body and upper-body explosive strength and throwing velocity in handball players. J Strength Cond Res 36(11): 3167-3172, 2022-The purpose of this study was to determine the acute effects of handball-specific high-intensity interval training (HIIT) on explosive strength and throwing velocity, after varying periods of recovery. Fourteen highly trained male handball players (age: 25.4 (26.2 ± 4.2) performed HIIT consisting of repeated 15-second shuttle runs at 90% of final running speed (V IFT ) to exhaustion . Upper-body and lower-body explosive strength and throwing velocities were measured before and immediately after HIIT, as well as after 6 hours. These tests included 3 repetitions of both bench press and squat exercise at 60% of the 1 repetition maximum (1RM) as well as 3 repetitions of the set shot without run up and jump shot, respectively. Explosive squat performance was significantly reduced at post (-5.48%, p = 0.026) but not at 6 h (-0.24%, p = 1.000). Explosive bench press performance remained statistically unaltered at post (0.32%, p = 1.000) and at 6 hour (1.96%, p = 1.000). This was also observed in the subsequent throws both immediately after (-0.60%, p = 1.000) (-0.31%, p = 1.000) and at 6 h (-1.58%, p = 1.000) (1.51%, p = 0.647). Our data show a reduction in explosive strength of the lower but not upper extremities when preceded by running HIIT. Since throwing velocity was not affected by intense lower-body exercise, combining lower-body HIIT and throwing practice may be of no concern in highly trained handball players.

Maximal isometric strength indices are associated with the oxygen cost of walking and running in recreationally active men and women.

This study assessed the associations of maximal isometric strength and movement economy in 126 recreationally active men and women. Oxygen consumption was assessed through a graded treadmill test with 4-minute increments (4-12 km∙h-1). Maximal isometric leg extensor, leg flexor and handgrip strength were assessed by isometric dynamometry. Models of best fit for gross oxygen cost and gross caloric unit cost were observed across the majority of velocities when the leg extensor/flexor strength ratio and handgrip strength were combined (R2 = 0.207-0.525 and R2 = 0.152-0.475, respectively). Additionally, the oxygen cost differed statistically for the majority of velocities when participants were split by the median of leg extensor strength (12.3-26.3 ml∙kg-1∙km-1, p < 0.05) and the average of all strength variables (13.9-30.3 ml∙kg-1∙km-1, p < 0.05). Our data underline the importance of maintaining maximal strength in order to perform activities with low to moderate oxygen demands.

Long-term physical training in adolescent sprint and middle distance swimmers alters the composition of circulating T and NK cells which correlates with soluble ICAM-1 serum concentrations.

PURPOSE: It remains unknown how different training intensities and volumes chronically impact circulating lymphocytes and cellular adhesion molecules. First, we aimed to monitor changes in NK and T cells over a training season and relate these to training load. Second, we analyzed effects of training differences between swimmers on these cells. Finally, we examined if changes in lymphocytes were associated with sICAM-1 concentrations. METHODS: We analyzed weekly training volume, training intensity, proportions of T and NK cells and serum sICAM-1 in eight sprint (SS) and seven middle-distance swimmers (MID) at three points over a 16-week training period: at the start (t0), after 7 weeks of increased training load (t7) and after 16 weeks, including 5-day taper (t16). RESULTS: Training volume of all swimmers was statistically higher and training intensity lower from t0-t7 compared to t7-t16 (p = 0.001). Secondly, training intensity was statistically higher in SS from t0-t7 (p = 0.004) and t7-t16 (p = 0.015), while MID had a statistically higher training volume from t7-t16 (p = 0.04). From t0-t7, NK (p = 0.06) and CD45RA+CD45RO+CD4+ cells (p < 0.001) statistically decreased, while CD45RA-CD45RO+CD4+ cells (p = 0.024) statistically increased. In a subgroup analysis, SS showed statistically larger increases in NK cells from t7-t16 than MID (p = 0.012). Lastly, sICAM-1 concentrations were associated with changes in CD45RA-CDRO+CD4+ cells (r = - 0.656, p = 0.08). CONCLUSION: These results indicate that intensified training in swimmers resulted in transient changes in T and NK cells. Further, NK cells are sensitive to high training volumes. Lastly, sICAM-1 concentrations may be associated with the migration and maturation of CD4+ cells in athletes.

H-reflex and M-wave responses after voluntary and electrically evoked muscle cramping.

PURPOSE: Despite the widespread occurrence of muscle cramps, their underlying neurophysiological mechanisms remain unknown. To better understand the etiology of muscle cramps, this study investigated acute effects of muscle cramping induced by maximal voluntary isometric contractions (MVIC) and neuromuscular electrical stimulation (NMES) on the amplitude of Hoffmann reflexes (H-reflex) and compound muscle action potentials (M-wave). METHODS: Healthy men (n = 14) and women (n = 3) participated in two identical sessions separated by 7 days. Calf muscle cramping was induced by performing MVIC of the plantar flexors in a prone position followed by 2.5-s NMES over the plantar flexors with increasing frequency and intensity. H-reflexes and M-waves evoked by tibial nerve stimulation in gastrocnemius medialis (GM) and soleus were recorded at baseline, and after MVIC-induced cramps and the NMES protocol. RESULTS: Six participants cramped after MVIC, and H-reflex amplitude decreased in GM and soleus in Session 1 (- 33 ± 32%, - 34 ± 33%, p = 0.031) with a similar trend in Session 2 (5 cramped, p = 0.063), whereas the maximum M-wave was unchanged. After NMES, 11 (Session 1) and 9 (Session 2) participants cramped. H-reflex and M-wave recruitment curves shifted to the left in both sessions and muscles after NMES independent of cramping (p ≤ 0.001). CONCLUSION: Changes in H-reflexes after a muscle cramp induced by MVIC and NMES were inconsistent. While MVIC-induced muscle cramps reduced H-reflex amplitude, muscle stretch to end cramping was a potential contributing factor. By contrast, NMES may potentiate H-reflexes and obscure cramp-related changes. Thus, the challenge for future studies is to separate the neural consequences of cramping from methodology-based effects.

Recommendations for determining the validity of consumer wearable heart rate devices: expert statement and checklist of the INTERLIVE Network.

Assessing vital signs such as heart rate (HR) by wearable devices in a lifestyle-related environment provides widespread opportunities for public health related research and applications. Commonly, consumer wearable devices assessing HR are based on photoplethysmography (PPG), where HR is determined by absorption and reflection of emitted light by the blood. However, methodological differences and shortcomings in the validation process hamper the comparability of the validity of various wearable devices assessing HR. Towards Intelligent Health and Well-Being: Network of Physical Activity Assessment (INTERLIVE) is a joint European initiative of six universities and one industrial partner. The consortium was founded in 2019 and strives towards developing best-practice recommendations for evaluating the validity of consumer wearables and smartphones. This expert statement presents a best-practice validation protocol for consumer wearables assessing HR by PPG. The recommendations were developed through the following multi-stage process: (1) a systematic literature review based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses, (2) an unstructured review of the wider literature pertaining to factors that may introduce bias during the validation of these devices and (3) evidence-informed expert opinions of the INTERLIVE Network. A total of 44 articles were deemed eligible and retrieved through our systematic literature review. Based on these studies, a wider literature review and our evidence-informed expert opinions, we propose a validation framework with standardised recommendations using six domains: considerations for the target population, criterion measure, index measure, testing conditions, data processing and the statistical analysis. As such, this paper presents recommendations to standardise the validity testing and reporting of PPG-based HR wearables used by consumers. Moreover, checklists are provided to guide the validation protocol development and reporting. This will ensure that manufacturers, consumers, healthcare providers and researchers use wearables safely and to its full potential.

Recommendations for determining the validity of consumer wearable and smartphone step count: expert statement and checklist of the INTERLIVE network.

Consumer wearable and smartphone devices provide an accessible means to objectively measure physical activity (PA) through step counts. With the increasing proliferation of this technology, consumers, practitioners and researchers are interested in leveraging these devices as a means to track and facilitate PA behavioural change. However, while the acceptance of these devices is increasing, the validity of many consumer devices have not been rigorously and transparently evaluated. The Towards Intelligent Health and Well-Being Network of Physical Activity Assessment (INTERLIVE) is a joint European initiative of six universities and one industrial partner. The consortium was founded in 2019 and strives to develop best-practice recommendations for evaluating the validity of consumer wearables and smartphones. This expert statement presents a best-practice consumer wearable and smartphone step counter validation protocol. A two-step process was used to aggregate data and form a scientific foundation for the development of an optimal and feasible validation protocol: (1) a systematic literature review and (2) additional searches of the wider literature pertaining to factors that may introduce bias during the validation of these devices. The systematic literature review process identified 2897 potential articles, with 85 articles deemed eligible for the final dataset. From the synthesised data, we identified a set of six key domains to be considered during design and reporting of validation studies: target population, criterion measure, index measure, validation conditions, data processing and statistical analysis. Based on these six domains, a set of key variables of interest were identified and a 'basic' and 'advanced' multistage protocol for the validation of consumer wearable and smartphone step counters was developed. The INTERLIVE consortium recommends that the proposed protocol is used when considering the validation of any consumer wearable or smartphone step counter. Checklists have been provided to guide validation protocol development and reporting. The network also provide guidance for future research activities, highlighting the imminent need for the development of feasible alternative 'gold-standard' criterion measures for free-living validation. Adherence to these validation and reporting standards will help ensure methodological and reporting consistency, facilitating comparison between consumer devices. Ultimately, this will ensure that as these devices are integrated into standard medical care, consumers, practitioners, industry and researchers can use this technology safely and to its full potential.

Oral Contraceptives Do Not Affect Physiological Responses to Strength Exercise.

ABSTRACT: Umlauff, L, Weil, P, Zimmer, P, Hackney, AC, Bloch, W, and Schumann, M. Oral contraceptives do not affect physiological responses to strength exercise. J Strength Cond Res 35(4): 894-901, 2021-This study investigated the effect of oral contraceptive (OC) use on acute changes in steroid hormone concentrations and tryptophan (TRP) metabolites in response to strength exercise. Twenty-one women (age: 23 ± 3 years), 8 combined OC users (OC group) and 13 naturally cycling women (menstrual cycle [MC] group), participated. Testing was performed during the pill-free interval for the OC group and the follicular phase for the MC group. Subjects completed an intense strength exercise protocol (4 × 10 repetitions back squat). Blood samples were taken at baseline (T0), post-exercise (T1), and after 24 hours (T2) to determine serum concentrations of cortisol, estradiol, testosterone, TRP, and kynurenine (KYN). Statistical significance was defined as p ≤ 0.05. At T0, the OC group showed higher cortisol (OC: 493.7 ± 47.1 ng·mL-1, MC: 299.1 ± 62.7 ng·mL-1, p < 0.001) and blood lactate (OC: 1.81 ± 0.61 mmol·L-1, MC: 1.06 ± 0.30 mmol·L-1, p = 0.001) and lower estradiol (OC: 31.12 ± 4.24 pg·mL-1, MC: 38.34 ± 7.50 pg·mL-1, p = 0.023) and KYN (OC: 1.15 ± 0.23 µmol·L-1, MC: 1.75 ± 0.50 µmol·L-1, p = 0.005). No significant interactions (group × time, p > 0.05) were found for the hormones and TRP metabolites assessed. Oral contraceptive use did not affect the physiological response of steroid hormones and TRP metabolites to acute strength exercise during the low hormone phase of the contraceptive or MC in healthy young women, even when some baseline concentrations differed between groups. Consequently, these findings provide important implications for practitioners testing heterogeneous groups of female athletes.

Comparison of two different cooling systems in alleviating thermal and physiological strain during prolonged exercise in the heat.

This study compared the efficacy of an ice vest comprising of water (WATER) or a water-carbon (CARBON) emulsion on thermophysiological responses to strenuous exercise in the heat. Twelve male cyclists completed three 50-minute constant workload trials (55% of peak power output, ambient temperature 30.4 ± 0.6°C) with WATER, CARBON, and without ice vest (CONTROL), respectively. The increase in core body temperature (Tcore) was lower in WATER at 40 (-0.49 ± 0.34 °C) and 50 minutes (-0.48 ± 0.48 °C) and in CARBON at 30 (-0.41 ± 0.48 °C), 40 (-0.54 ± 0.51 °C), and 50 minutes (-0.67 ± 0.62 °C) as compared to CONTROL (p < 0.05, ES > 0.8). While heart rate and blood lactate kinetics did not differ between the conditions, statistical main effects in favour of both WATER and CARBON were found for thermal sensation (condition p < 0.001 and interaction p < 0.01) and rating of perceived exertion (condition p < 0.05). Per-cooling with CARBON and WATER similarly reduced Tcore but not physiological strain during prolonged exercise in the heat. Practitioner Summary: Exercise in the heat is characterised by increases in thermophysiological strain. Both per-cooling with a novel carbon-based and a conventional water-based ice vest were shown to reduce core temperature significantly. However, due to its lower mass, the carbon-based system may be recommended especially for weight-bearing sports.

Acute hypertrophic but not maximal strength loading transiently enhances the kynurenine pathway towards kynurenic acid.

PURPOSE: Due to distinct immuno- and neuro-modulatory properties, growing research interest focuses on exercise-induced alterations of the kynurenine (KYN) pathway in healthy and clinical populations. To date, knowledge about the impact of different acute strength exercise modalities on the KYN pathway is scarce. Therefore, we investigated the acute effects of hypertrophic (HYP) compared to maximal (MAX) strength loadings on the KYN pathway regulation. METHODS: Blood samples of twelve healthy males (mean age and weight: 23.5 ± 3.2 years; 77.5 ± 7.5 kg) were collected before (T0), immediately after (T1), and 1 h after completion (T2) of HYP (5 sets with 10 repetitions at 80% of 1RM) and MAX (15 sets with 1RM) loadings performed in a randomized cross-over design. Serum concentrations of tryptophan (TRP), KYN, kynurenic acid (KA), and quinolinic acid (QA) were assessed using high-performance liquid chromatography. RESULTS: The KA/KYN ratio increased from T0 to T1 (p = 0.01) and decreased from T1 to T2 (p = 0.011) in HYP, while it was maintained within MAX. Compared to MAX, serum concentrations of KA were greater in HYP at T1 (p = 0.014). Moreover, the QA/KA ratio was significantly lower in HYP than in MAX at T1 (p = 0.002). CONCLUSION: Acute HYP loading led to increases in the metabolic flux yielding KA, thereby possibly promoting immunosuppression and neuroprotection. Our findings emphasize the potential of acute HYP exercise as short-term modulator of KYN pathway downstream to KA in healthy males and need to be proven in other samples.

Effects of Periodized vs. Nonperiodized Resistance Training on Army-Specific Fitness and Skills Performance.

Heilbronn, BE, Doma, K, Gormann, D, Schumann, M, and Sinclair, WH. Effects of periodized vs. nonperiodized resistance training on army-specific fitness and skills performance. J Strength Cond Res 34(3): 738-753, 2020-This study investigated the effects of periodized resistance training (PRD) and nonperiodized resistance training (NPRD) on army-specific fitness and skills performance measures. Forty-nine serving members of the Australian Army were randomly assigned to 1 of 3 training groups: PRD, NPRD, or no-resistance training (NRT). Resistance training (RT) was performed during PRD and NPRD twice a week for 9 weeks, over a 15-week period, as part of a structured strength and conditioning program. Baseline, mid- and post-testing measures included anthropometric, strength, and army-specific outcome measures. Results indicated that participants who undertook RT significantly improved in 3 repetition maximum (3RM) squat, deadlift, and floor press for both RT groups, at mid- and post-testing (p < 0.05), when compared with NRT. Significant improvements were also observed in 5-km weight load marching postintervention similarly for PRD (p < 0.05) and NPRD (p < 0.01) and simulated fire and movement for both RT groups at both time points (p < 0.01), compared with the NRT group (p > 0.05). Although little difference was observed between periodization models, the current findings suggest greater advantage in developing army-specific performances if a structured RT protocol is included in a generic physical training program compared with a NRT protocol. Therefore, a structured RT program should be considered for military personnel aiming to optimize army-specific fitness and skills performance.

Physiological adaptations to resistance training in rats selectively bred for low and high response to aerobic exercise training.

NEW FINDINGS: What is the central question of this study? Can phenotypic traits associated with low response to one mode of training be extrapolated to other exercise-inducible phenotypes? The present study investigated whether rats that are low responders to endurance training are also low responders to resistance training. What is the main finding and its importance? After resistance training, rats that are high responders to aerobic exercise training improved more in maximal strength compared with low-responder rats. However, the greater gain in strength in high-responder rats was not accompanied by muscle hypertrophy, suggesting that the responses observed could be mainly neural in origin. ABSTRACT: The purpose of this study was to determine whether rats selectively bred for low and high response to aerobic exercise training co-segregate for differences in muscle adaptations to ladder-climbing resistance training. Five high-responder (HRT) and five low-responder (LRT) rats completed the resistance training, while six HRT and six LRT rats served as sedentary control animals. Before and after the 6 week intervention, body composition was determined by dual energy X-ray absorptiometry. Before tissue harvesting, the right triceps surae muscles were loaded by electrical stimulation. Muscle fibre cross-sectional areas, nuclei per cell, phosphorylation status of selected signalling proteins of mTOR and Smad pathways, and muscle protein, DNA and RNA concentrations were determined for the right gastrocnemius muscle. The daily protein synthesis rate was determined by the deuterium oxide method from the left quadriceps femoris muscle. Tissue weights of fore- and hindlimb muscles were measured. In response to resistance training, maximal carrying capacity was greater in HRT (∼3.3 times body mass) than LRT (∼2.5 times body mass), indicating greater improvements of strength in HRT. However, muscle hypertrophy that could be related to greater strength gains in HRT was not observed. Furthermore, noteworthy changes within the experimental groups or differences between groups were not observed in the present measures. The lack of hypertrophic muscular adaptations despite considerable increases in muscular strength suggest that adaptations to the present ladder-climbing training in HRT and LRT rats were largely induced by neural adaptations.

Anatomical versus functional motor points of selected upper body muscles.

INTRODUCTION: In this study we aimed to identify nerve entry points (NEPs) of superficial skeletal muscles obtained by dissection of 20 human cadavers and compared them with motor points (MP) obtained previously by electrical stimulation. METHODS: The biceps brachii (BB), trapezius (TZ), latissimus dorsi (LD), pectoralis major (Pmaj), and pectoralis minor (Pmin) muscles were dissected from human cadavers. NEP data (mean ± standard deviation) from each muscle were calculated. F-tests with Bonferroni corrections were used to compare NEPs and MPs. RESULTS: The number of NEPs was 2 in BB, 1 in Pmin, 4 in TZ, and 3 in LD, whereas the total number in Pmaj varied from 3 to 5. NEPs and MPs were statistically equal only in Pmin and in the descending part of TZ. DISCUSSION: The findings show crucial differences between NEPs and MPs, possibly impacting the effectiveness of several medical treatment strategies. Muscle Nerve 57: 460-465, 2018.