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.

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.

Autologous Blood Doping Induced Changes in Red Blood Cell Rheologic Parameters, RBC Age Distribution, and Performance.

Autologous blood doping (ABD) refers to the transfusion of one's own blood after it has been stored. Although its application is prohibited in sports, it is assumed that ABD is applied by a variety of athletes because of its benefits on exercise performance and the fact that it is not detectable so far. Therefore, this study aims at identifying changes in hematological and hemorheological parameters during the whole course of ABD procedure and to relate those changes to exercise performance. Eight healthy men conducted a 31-week ABD protocol including two blood donations and the transfusion of their own stored RBC volume corresponding to 7.7% of total blood volume. Longitudinal blood and rheological parameter measurements and analyses of RBC membrane proteins and electrolyte levels were performed. Thereby, responses of RBC sub-populations-young to old RBC-were detected. Finally, exercise tests were carried out before and after transfusion. Results indicate a higher percentage of young RBC, altered RBC deformability and electrolyte concentration due to ABD. In contrast, RBC membrane proteins remained unaffected. Running economy improved after blood transfusion. Thus, close analysis of RBC variables related to ABD detection seems feasible but should be verified in further more-detailed studies.

Validity of Estimating the Maximal Oxygen Consumption by Consumer Wearables: A Systematic Review with Meta-analysis and Expert Statement of the INTERLIVE Network.

BACKGROUND: Technological advances have recently made possible the estimation of maximal oxygen consumption (VO2max) by consumer wearables. However, the validity of such estimations has not been systematically summarized using meta-analytic methods and there are no standards guiding the validation protocols. OBJECTIVE: The aim was to (1) quantitatively summarize previous studies investigating the validity of the VO2max estimated by consumer wearables and (2) provide best-practice recommendations for future validation studies. METHODS: First, we conducted a systematic review and meta-analysis of studies validating the estimation of VO2max by wearables. Second, based on the state of knowledge (derived from the systematic review) combined with the expert discussion between the members of the Towards Intelligent Health and Well-Being Network of Physical Activity Assessment (INTERLIVE) consortium, we provided a set of best-practice recommendations for validation protocols. RESULTS: Fourteen validation studies were included in the systematic review and meta-analysis. Meta-analysis results revealed that wearables using resting condition information in their algorithms significantly overestimated VO2max (bias 2.17 ml·kg-1·min-1; limits of agreement - 13.07 to 17.41 ml·kg-1·min-1), while devices using exercise-based information in their algorithms showed a lower systematic and random error (bias - 0.09 ml·kg-1·min-1; limits of agreement - 9.92 to 9.74 ml·kg-1·min-1). The INTERLIVE consortium proposed six key domains to be considered for validating wearable devices estimating VO2max, concerning the following: the target population, reference standard, index measure, testing conditions, data processing, and statistical analysis. CONCLUSIONS: Our meta-analysis suggests that the estimations of VO2max by wearables that use exercise-based algorithms provide higher accuracy than those based on resting conditions. The exercise-based estimation seems to be optimal for measuring VO2max at the population level, yet the estimation error at the individual level is large, and, therefore, for sport/clinical purposes these methods still need improvement. The INTERLIVE network hereby provides best-practice recommendations to be used in future protocols to move towards a more accurate, transparent and comparable validation of VO2max derived from wearables. PROSPERO ID: CRD42021246192.

Hormonal response after masturbation in young healthy men - a randomized controlled cross-over pilot study.

BACKGROUND: Hormones like testosterone play a crucial role in performance enhancement and muscle growth. Therefore, various attempts to increase testosterone release and testosterone concentration have been made, especially in the context of resistance training. Among practitioners, sexual activity (coitus and masturbation) a few hours before training is often discussed to result in increases of testosterone concentration and thus promote muscle growth. However, there is no evidence to support this assumption and the kinetics of the testosterone and cortisol response after sexual activity have not been adequately investigated. Therefore, the aim of this pilot-study was to examine the kinetics of hormone concentrations of total testosterone, free testosterone and cortisol and their ratios after masturbation. In a three-arm single blinded cross-over study, the effects of masturbation with visual stimulus were compared to a visual stimulus without masturbation and the natural kinetics in healthy young men. RESULTS: The results showed a significant between-condition difference in free testosterone concentrations. Masturbation (p < 0.01) and a visual stimulus (p < 0.05) may seem to counteract the circadian drop of free testosterone concentrations over the day. However, no statistical change was observed in the ratios between total testosterone, free testosterone and cortisol. CONCLUSIONS: It can be assumed that masturbation may have a potential effect on free testosterone concentrations but not on hormonal ratios. However, additional studies with larger sample sizes are needed to validate these findings.

RéSUMé: CONTEXTE: Les hormones comme la testostérone jouent un rôle crucial dans l'amélioration des performances et dans la croissance musculaire. Par conséquent, diverses tentatives pour augmenter la libération de testostérone et la concentration de testostérone ont été faites, en particulier dans le contexte de l'entraînement à la résistance. Chez les praticiens, l'activité sexuelle (le coït et la masturbation) quelques heures avant l'entraînement est souvent évoquée comme induisant une augmentation de la concentration de testostérone et favorisant ainsi la croissance musculaire. Il n'existe, cependant, aucune preuve à l'appui de cette hypothèse et la cinétique de la réponse de la testostérone et du cortisol après l'activité sexuelle n'a pas été étudiée de manière adéquate. Par conséquent, l'objectif de cette étude pilote était d'examiner la cinétique des concentrations hormonales de testostérone totale, de testostérone libre et de cortisol et de leurs ratios après la masturbation. Dans une étude croisée à trois bras en simple aveugle, les effets de la masturbation avec stimulus visuel ont été comparés à un stimulus visuel sans masturbation et à la cinétique naturelle chez des hommes jeunes en bonne santé. RéSULTATS: Les résultats ont montré, pour les concentrations de testostérone libre, une différence significative entre les conditions. La masturbation (p < 0,01) et un stimulus visuel (p < 0,05) pourraient sembler contrecarrer la baisse circadienne des concentrations de testostérone libre au cours de la journée. Cependant, aucun changement statistique n'a été observé dans les ratios entre la testostérone totale, la testostérone libre et le cortisol. CONCLUSION: On peut supposer que la masturbation peut avoir un effet potentiel sur la testostérone libre mais pas sur les ratios hormonaux. D'autres études, avec des échantillons de plus grande taille, sont cependant nécessaires pour valider ces résultats.

Cooling During Endurance Cycling in the Heat: Blunted Core Temperature but Not Inflammatory Responses.

PURPOSE: This study assessed the effects of cooling during endurance cycling (percooling) on changes in core body temperature (Tcore), inflammatory, and metabolic responses. METHODS: A total of 12 male cyclists (peak oxygen uptake 60 [4] mL·kg-1·min-1) completed a 60-minute constant workload trial (55% of peak power output and ambient temperature 30.4°C [0.6°C]) in a randomized order both with (ICE) and without (CON) an ice vest. An ingestible capsule was used to measure Tcore. Blood samples were collected immediately before and after each trial to determine concentrations of blood lactate, serum cortisol, interleukin-6, and reactive oxygen and nitrogen species. RESULTS: Tcore increased statistically (P < .001) both in CON (7.0% [1.4%], effect size [ES] = 6.3) and ICE (5.1% [1.1%], ES = 5.7). The increase in CON was statistically larger compared with ICE (P = .006, ES = 1.4). Concentrations of blood lactate (CON: 163% [63%], ES = 1.3; ICE: 149% [91%], ES = 1.3), cortisol (CON: 138% [123%], ES = 1.7; ICE: 81% [102%], ES = 1.0), and interleukin-6 (CON: 661% [324%], ES = 2.1; ICE: 624% [368%], ES = 1.2) statistically increased in both conditions (P < .01) to a similar extent. In addition, reactive oxygen and nitrogen species statistically decreased in both conditions (CON: -19.2% [14.9%], P = .002, ES = 0.9; ICE: -15.1% [16.5%], P = .02, ES = 0.9). No correlations were found between the changes of Tcore and blood parameters across the conditions. CONCLUSIONS: Despite attenuated Tcore, similar inflammatory and metabolic responses were observed. Our findings suggest percooling to be a promising strategy to attenuate thermal strain without compromising physiological function.

Short-Term Creatine Loading Improves Total Work and Repetitions to Failure but Not Load-Velocity Characteristics in Strength-Trained Men.

This study assessed the effects of a 7-day creatine (CRE) supplementation on the load-velocity profile and repeated sub-maximal bouts in the deep squat using mean propulsive velocity (MPV) and mean propulsive power (MPP). Eleven strength-trained men (31.4 ± 5.4 years) supplemented 0.3 g·kg-1·d-1 CRE or a placebo (PLA, maltodextrin) for seven days in a randomized order, separated by a 30-day washout period. Prior to and after the supplementation, the subjects performed an incremental maximal strength (1RM) test, as well as 3 × 10 repetitions and a repetitions-to-failure test (RFT), all at 70% 1RM. Maximal strength remained statistically unaltered in CRE (p = 0.107) and PLA (p = 0.568). No statistical main effect for time (p = 0.780) or interaction (p = 0.737) was observed for the load-velocity profile. The number of repetitions during RFT remained statistically unaltered in both conditions (CRE: +16.8 ± 32.8%, p = 0.112; PLA: +8.2 ± 47.2%, p = 0.370), but the effect size was larger in creatine compared to placebo (g = 0.51 vs. g = 0.01). The total work during RFT increased following creatine supplementation (+23.1 ± 35.9%, p = 0.043, g = 0.70) but remained statistically unaltered in the placebo condition (+15.0 ± 60.8%, p = 0.801, g = 0.08; between conditions: p = 0.410, g = 0.25). We showed that CRE loading over seven days did not affect load-velocity characteristics but may have increased total work and power output during submaximal deep squat protocols, as was indicated by moderate effect sizes.

Metabolic, hormonal and performance effects of isomaltulose ingestion before prolonged aerobic exercise: a double-blind, randomised, cross-over trial.

BACKGROUND: Isomaltulose has been discussed as a low glycaemic carbohydrate but evidence concerning performance benefits and physiological responses has produced varying results. Therefore, we primarily aimed to investigate the effects of isomaltulose ingestion compared to glucose and maltodextrin on fat and carbohydrate oxidation rates, blood glucose levels and serum hormone concentrations of insulin and glucose-dependent insulinotropic polypeptide (GIP). As secondary aims, we assessed running performance and gastrointestinal discomfort. METHODS: Twenty-one male recreational endurance runners performed a 70-min constant load trial at 70% maximal running speed (Vmax), followed by a time to exhaustion (TTE) test at 85% Vmax after ingesting either 50 g isomaltulose, maltodextrin or glucose. Fat and carbohydrate oxidation rates were calculated from spiroergometric data. Venous blood samples for measurement of GIP and insulin were drawn before, after the constant load trial and after the TTE. Capillary blood samples for glucose concentrations and subjective feeling of gastrointestinal discomfort were collected every 10 min during the constant load trial. RESULTS: No between-condition differences were observed in the area under the curve analysis of fat (p = 0.576) and carbohydrate oxidation rates (p = 0.887). Isomaltulose ingestion led to lower baseline postprandial concentrations of blood glucose compared to maltodextrin (percent change [95% confidence interval], - 16.7% [- 21.8,-11.6], p < 0.001) and glucose (- 11.5% [- 17.3,-5.7], p = 0.001). Similarly, insulin and GIP concentrations were also lower following isomaltulose ingestion compared to maltodextrin (- 40.3% [- 50.5,-30.0], p = 0.001 and - 69.1% [- 74.3,-63.8], p < 0.001, respectively) and glucose (- 32.6% [- 43.9,-21.2], p = 0.012 and - 55.8% [- 70.7,-40.9], p < 0.001, respectively). Furthermore, glucose fluctuation was lower after isomaltulose ingestion compared to maltodextrin (- 26.0% [- 34.2,-17.8], p < 0.001) and glucose (- 17.4% [- 29.1,-5.6], p < 0.001). However, during and after exercise, no between-condition differences for glucose (p = 0.872), insulin (p = 0.503) and GIP (p = 0.244) were observed. No between-condition differences were found for TTE (p = 0.876) or gastrointestinal discomfort (p = 0.119). CONCLUSION: Isomaltulose ingestion led to lower baseline postprandial concentrations of glucose, insulin and GIP compared to maltodextrin and glucose. Consequently, blood glucose fluctuations were lower during treadmill running after isomaltulose ingestion, while no between-condition differences were observed for CHO and fat oxidation rates, treadmill running performance and gastrointestinal discomfort. Further research is required to provide specific guidelines on supplementing isomaltulose in performance and health settings.