Acute Hormonal Responses Research Articles

Effects of time-of-day resistance training on muscle strength, hormonal adaptations, and sleep quality during Ramadan fasting

ObjectivesWe investigated the timing of resistance training (RT) during Ramadan fasting (RF) on muscle strength, hormonal adaptations, and sleep quality.MethodsForty healthy and physically active male Muslims (age = 25.7 ± 5.6 years, body mass = 85.1 ± 17.5 kg, height = 175 ± 9 cm, BMI = 28.3 ± 5.7 kg/m2) were enrolled in this study and 37 completed pre and post-tests. Subjects were randomly allocated into two experimental groups. Group 1 (FAST, n = 20) completed an 8-week whole-body RT in the late afternoon (between 16 h and 18 h) while fasting. Group 2 (FED, n = 20) completed the similar RT protocol compared with FAST at night (between 20 h and 22 h). The following parameters were analyzed at various time-points: 2 weeks before the start of RF (T0), on the 15th day of Ramadan (T1), on the 29th day of Ramadan (T2), and 21 days after the last day of RF (T3) where both groups were in a fed state. One-repetition maximum tests (1-RM) were conducted for the squats (1-RMSQ), the deadlift (1-RMDL) and the bench press (1-RMBP). Sleep quality was assessed using the full Pittsburgh Sleep Quality Index (PSQI). Blood samples were taken to determine cortisol, testosterone and IGF-1 levels. Additionally, acute hormonal responses were evaluated before (BF), immediately after (AF), and 30 min after a RT session (AF-30 min) at T0, T1, T2, and T3.ResultsSignificant group-by-time interactions were identified for 1-RMSQ (p = 0.001; effect size [ES] = 0.43) and 1-RMDL (p = 0.001; ES = 0.36). Post-hoc tests indicated significant 1-RMSQ (p = 0.03; ES = 0.12) and 1-RMDL (p = 0.04; ES = 0.21) improvements from T0-T2 for FED. Additionally, significant group-by-time interactions were observed for the chronic effects on cortisol (p = 0.03; ES = 0.27) and testosterone levels (p = 0.01; ES = 0.32). Post-hoc tests indicated significant increases of cortisol levels among FAST at T1 and T2 compared to T0 (p = 0.05; ES = 0.41, p = 0.03; ES = 0.34) and a significant increase in cortisol levels in FED at T1 (p = 0.05; ES = 0.29) and T2 (p = 0.04; ES = 0.25). However, the observed increase was lower compared to FAST. Post-hoc tests also indicated significant increases of testosterone only among FED at T2 (p = 0.04; ES = 0.31). A significant group-by-time interaction was found for the acute effect of exercise on cortisol level (p = 0.04; ES = 0.34). The cortisol level immediately after RT was higher in FAST only at T1 (p = 0.03; ES = 0.39) and T2 (p = 0.05; ES = 0.22) compared with T0. No significant group-by-time interactions were identified for sleep quality (p = 0.07; ES = 0.43).ConclusionMuslims can safely practice RT during RF. However, training in a fed state during Ramadan might be more effective than during fasted state for the enhancement of maximal strength with better hormonal responses observed.

Acute Endocrine Responses With Long-Term Weight Lifting in a 51-Year-Old Male Weightlifter.

Eserhaut, DA, Fry, AC, Stone, MH, and Kraemer, WJ. Acute endocrine responses with long-term weightlifting in a 51 year old male weightlifter. J Strength Cond Res XX(X): 000-000, 2024-To study the effects of long-term (>35 years) competitive weightlifting on acute endocrine activity, a 51-year-old male two-time Olympian in weightlifting (Subject A) was compared with highly trained young male weightlifters (controls, n = 23; age = 17.7 ± 0.3 years). Between 1400 and 1700 hours, subjects performed 15 maximum effort vertical jumps, a series of single repetitions of the snatch progressing to a maximal effort, and 3 × 10 snatch pulls at 60% 1 repetition maximum. Blood sampling occurred at 0700 hours, pre-exercise, and +5 and +15 minutes postexercise. Exercise performances were comparable between Subject A and controls and elicited similar lactate responses at +5 minutes (mmol·L-1; A = 9.2; controls = 8.1 ± 0.4). Resting testosterone at 0700 hours was lower for Subject A than for the controls (nmol·L-1; A = 13.9; controls = 25.4 ± 2.0), although acute responses at +5 minutes were comparable (A = 21.6; controls 18.3 ± 1.5). Cortisol responses (nmol·L-1; A = 468.4, controls = 540.6 ± 32.3) and testosterone:cortisol ratio (A = 0.0461; controls = 0.0376 ± 0.004) were similar at +5 minutes. Subject A showed no 22 kDa growth hormone response at +5 minutes, while controls exhibited a substantial increase (µg·L-1; A = 0.4; controls = 16.7 ± 2.6). β-endorphin responses were no different at +15 minutes for Subject A relative to controls (pmol·L-1; A = 30.1; controls = 33.8 ± 3.7). Resting and exercise-induced endocrine physiology is partially modified with aging despite long-term participation in competitive weightlifting. Importantly, Subject A's testosterone response was largely preserved.

Hormonal and inflammatory responses in prepubertal vs. pubertal male children following an acute free-weight resistance training session.

Examine the acute hormonal and cytokine responses to free-weight resistance training in trained prepubertal and pubertal male children. Prepubertal (n = 21; age 11.4 ± 1.1years; Tanner I-II) and pubertal male children (n = 20; age 15.8 ± 0.7years; Tanner III-V) conducted a moderate-intensity free-weight resistance training program to failure with venous blood sampling before (pre), immediately after (post) and during the recovery phase of the program (post-15,-30min). Growth hormone (GH), insulin-like growth factor-I (IGF-I), cortisol, testosterone, IL-6, and TNF-α were analyzed in serum samples. Biological maturation was assessed according to the stages of the Tanner scale. There was a significant time-by-group interaction in IGF-I response (p = 0.044; η2 = 0.209) and testosterone (p < 0.001; η2 = 0.508), indicating a greater change in the pubertal group compared to the prepubertal group. Both groups significantly increased post-exercise GH levels (p < 0.05). Only the prepuberal group significantly increased levels of IL-6 at all post-exercise time points (p < 0.05). Both groups showed a significant (p < 0.05) increase in TNF-α levels compared to resting levels. These data suggest that acute testosterone and IGF-I response following resistance training differ between trained prepubertal and pubertal male children. Moderate-intensity resistance training performed to failure may thus have different effects in trained prepubertal and pubertal male children, which should be considered when giving training advice. Clinical trials number: NCT05022992.

Acute Hormonal and Inflammatory Responses following Lower and Upper Body Resistance Exercises Performed to Volitional Failure.

This study aimed to investigate the effects of a single bench press (BP) vs. leg press (LP) resistance training sessions on testosterone, cortisol, C-reactive protein (CRP) interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) concentrations, and creatine kinase (CK) activity in strength-trained males. Eleven strength-trained males participated in a cross-over randomized trial, undergoing two experimental sessions each consisting of five sets of the BP or the LP exercise to volitional failure with a load corresponding to 50% of one-repetition maximum. Blood samples were taken at baseline (BA), immediately post (POST), and 1 h after the cessation of exercise (POST-1). A significant increase in IL-6 concentration from BA to POST-1 was observed during the LP condition (p = 0.004; effect size [ES] = 0.64). Additionally, a significant main effect of time was found for increasing testosterone concentrations from BA to POST exercise (p = 0.014; ES = 0.25). A significantly lower cortisol concentration at POST-1 compared to POST (p = 0.001; ES = 1.02) was noted in the BP condition. Furthermore, a significantly lower cortisol concentration was found at POST-1 in the BP compared to the LP condition (p = 0.022; ES = 1.3). A significant increase in CK activity was reported from BA to POST (p = 0.024; ES = 0.69) and POST-1 (p = 0.045; ES = 0.55) during the LP condition, and from BA to POST-1 (p = 0.014; ES = 0.96) during the BP condition. No significant differences were found in the CRP (p = 0.659) and TNF-α concentrations (p = 0.487). These results suggest that the amount of muscle mass engaged during the resistance exercise may influence the changes in IL-6 and cortisol concentrations. Larger muscle groups, as engaged in the LP, more likely lead to elevated concentrations of IL-6 myokine.

Maturity-Associated Longitudinal Variations in Exercise-Induced Acute Hormonal Responses in Adolescent Male Athletes.

To examine longitudinal changes in exercise-induced hormonal responses in adolescent male basketball players. Fifteen adolescent males were assigned to prepeak height velocity (pre-PHV) and post-PHV groups according to the predicted age at PHV. Salivary testosterone, cortisol levels, and the testosterone-to-cortisol ratio were evaluated before (PRE), immediately after (POST), and 15minutes after a bodyweight resistance training session, which was repeated after 1year to analyze longitudinal changes in testosterone and cortisol levels. Resting testosterone levels and acute testosterone responses after bodyweight resistance training increased in both groups after 1year at all measurement points. The POST testosterone levels at initial measurement and PRE and 15-minute postexercise levels at 1year in the post-PHV group were significantly higher than those in the pre-PHV group. Cortisol levels significantly decreased in the post-PHV group at baseline and 1year later. In the post-PHV, the testosterone-to-cortisol ratio after bodyweight resistance training was significantly increased at baseline and 1year later. Although testosterone levels increase with age, no acute response to bodyweight resistance training was observed after 1year. The change in anabolic status indicated by the testosterone-to-cortisol ratio was due to a decrease in cortisol levels.

Acute Hormonal Responses to Multi-Joint Resistance Exercises with Blood Flow Restriction.

The purpose of this study was to investigate the acute effects of multi-joint resistance exercises (MJRE) with blood flow restriction on hormonal responses. Ten men participated in the study and underwent two experimental protocols in random order: four sets (30, 15, 15, and 15 reps, respectively) of MJRE (half squat and horizontal chest press) were performed with 20% of 1RM and a rest time between sets of 30 s, combined with intermittent blood flow restriction (LI + BFR protocol); and four sets (8, 8, 8, 20 reps, respectively) of the same MJRE performed with 75% of 1RM load (HI protocol), with a 90 s rest between the first three sets and 30 s between the third to the fourth set. Blood samples were collected before (PRE), immediately after (POST), and 15 min after the performance of MJRE (POST15). A time effect was observed for growth hormone (GH) and insulin-like-growth-factor-1-binding-protein-3 (IGFPB-3), but no protocol effects or interactions between protocol and times were observed (p > 0.05). There was no effect of either protocol or time (p > 0.05) on total testosterone, free testosterone, or cortisol concentrations. However, significant (p < 0.05) increases were observed in the GH serum concentrations of 2072.73% and 2278.5%, HI, and LI + BFR protocols, respectively, from the PRE to POST15 test. In addition, there was an increase of 15.30% and 13.29% in the IGFPB-3 concentrations (p < 0.05) from PRE to POST0 times for HI and LI + BFR protocols, respectively. Furthermore, there was a decrease of −6.17% and −11.54%, p = 0.00, between the times POST0 to POST15 in the IGFPB-3 for the HI and LI + BFR protocols, respectively. It is concluded that multi-joint resistance exercises combined with intermittent blood flow restriction seemed to promote acute hormonal responses in a manner similar to traditional exercise with high loads. Future studies may investigate whether chronic use of LI + BFR with MJRE may promote muscle hypertrophy.

Acute Hormonal Responses to Intentionally Slow or Maximal Velocity Resistance Exercise in Men

Acute Hormonal Responses to Intentionally Slow or Maximal Velocity Resistance Exercise in Men

Arousal/Stress Effects of "Overwatch" eSports Game Competition in Collegiate Gamers.

Kraemer, WJ, Caldwell, LK, Post, EM, Beeler, MK, Emerson, A, Volek, JS, Maresh, CM, Fogt, JS, Fogt, N, Häkkinen, K, Newton, RU, Lopez, P, Sanchez, BN, and Onate, JA. Arousal/stress effects of "Overwatch" eSports game competition in collegiate gamers. J Strength Cond Res 36(10): 2671-2675, 2022-To date, no physical response data are available for one of the most popular eSport games, Overwatch . The purpose of this investigation was to describe the stress signaling associated with competitive Overwatch play and to understand how acute hormonal responses may affect performance. Thirty-two male college-aged gamers (age: 21.3 ± 2.7 years; estimated time played per week: 18 ± 15 hours) completed the study. Subjects were randomly assigned to a 6-player team to compete in a tournament-style match. Salivary measures of cortisol and testosterone were collected immediately before (PRE) and after (POST) the first-round game, with the heart rate recorded continuously during the match. The mean characteristics were calculated for each variable and comparisons made by the skill level. Significance was defined as p ≤ 0.05. There were no differences in measures of salivary cortisol. A differential response pattern was observed by the skill level for testosterone. The low skill group displayed a significant increase in testosterone with game play (mean ± SD , testosterone PRE: 418.3 ± 89.5 pmol·L -1 , POST: 527.6 ± 132.4 pmol·L -1 , p < 0.001), whereas no change was observed in the high skill group. There were no differences in heart rate characteristics between skill groups. Overall, the average heart rate was 107.2 ± 17.8 bpm with an average max heart rate of 133.3 ± 19.1 bpm. This study provides unique physiological evidence that a sedentary Overwatch match modulates endocrine and cardiovascular responses, with the skill level emerging as a potential modulator.

Acute Hormonal Responses to Free Weight and Machine Resistance Exercise

Acute Hormonal Responses to Free Weight and Machine Resistance Exercise

Maturity-Associated Variations in Resistance Exercise-Induced Hormonal Responses in Young Male Athletes

To examine differences in resistance exercise-induced hormonal responses among young athletes according to their maturity levels. A total of 12 collegiate and 32 junior high school male athletes were enrolled. The junior high school participants were divided into pre-peak height velocity (PHV) and post-PHV groups, according to their PHV ages. The salivary testosterone, cortisol, and human growth hormone levels were analyzed before (pre), immediately after (post), and at 15minutes after performing body weight resistance exercise. The testosterone levels were higher in the collegiate than in the junior high school group (P < .01) and increased after 15minutes of exercise (P < .01). A significant decrease in the cortisol levels postexercise in the junior high school groups (P < .01) and an increase in the human growth hormone levels at 15minutes after exercise in the post-PHV group were observed (P < .01). In the collegiate and post-PHV groups, the testosterone-to-cortisol ratio increased post and at 15minutes after exercise (P < .01). The testosterone-to-cortisol ratio values were higher in the collegiate than in the post-PHV (at preexercise and at 15min after [P < .01]) and pre-PHV groups (at all times [P < .01]). Exercise-induced acute hormonal responses to resistance exercise may depend on individuals' maturity levels, even in those having the same age.

Behaviour of salivary testosterone and cortisol in men during an Ironman Triathlon

ABSTRACT Endurance exercise induces notable acute hormonal responses on the gonadal and adrenal hormones. The purpose of this study was to assess the changes in salivary testosterone (Ts), salivary cortisol (Cs) and T/C ratio during long-distance triathlon. Ten well-trained male triathletes participated in the study and were assessed for hormonal changes at four time-points (pre-competition, post-swimming, post-cycling, and post-running phases). Ts decreased from pre-competition to post-swimming (from 93.37 pg/mL to 57.63 pg/mL; p < .01) and increased during two other parts of the competition to almost pre-competition values (cycling: 79.20 pg/mL, p = .02; running: 89,66 pg/mL, p = .04, respectively). Cs showed a similar behaviour; decreasing in the post-swimming phase (1.74 pg/mL) and increasing in the other transitions (post-cycling: 7.30 pg/mL; post-running: 13.31 pg/mL), with significant differences between pre-competition and post- competition values (p = .01). Conversely, T/C increased significantly from pre-competition to post-swimming phase (p = .04) to later decrease until the end of the competition. Overall, T/C significantly decreased (p < .05). In conclusion, during an Ironman triathlon, hormone values fluctuate in response to the demands of the competition. Ts and Cs decrease after-swimming, increase after-cycling and reach the maximum values after-running. T/C reflects overall catabolic status.

Acute effect of HIIT on testosterone and cortisol levels in healthy individuals: A systematic review and meta-analysis.

To determine the acute effect of a single high-intensity interval training (HIIT) session on testosterone and cortisol levels in healthy individuals, a systematic search of studies was conducted in MEDLINE and Web of Science databases from inception to February 2020. Meta-analyses were performed to establish the acute effect of HIIT on testosterone and cortisol levels immediately after a single HIIT session; after 30min and 60min (primary outcomes); and after 120min, 180min, and 24h (secondary outcomes, only for pre-post intervention groups). Potential effect-size modifiers were assessed by meta-regression analyses and analyses of variance. Study quality was assessed using the Cochrane's risk of bias tool and the Physiotherapy Evidence Database scale. The meta-analyses of 10 controlled studies (213 participants) and 50 pre-post intervention groups (677 participants) revealed a significant increase in testosterone immediately after a single HIIT session (d=0.92 and 0.52, respectively), which disappeared after 30min (d=0.18 and -0.04), and returned to baseline values after 60min (d=-0.37 and -0.16). Significant increases of cortisol were found immediately after (d=2.17 and 0.64), after 30min (d=1.62 and 0.67) and 60min (d=1.32 and 0.27). Testosterone and cortisol levels decreased significantly after 120min (d=-0.48 and -0.95, respectively) and 180min (d=-0.29 and -1.08), and returned to baseline values after 24h (d=0.14 and -0.02). HIIT components and participant's characteristics seem to moderate the effect sizes. In conclusion, testosterone and cortisol increase immediately after a single HIIT session, then drop below baseline levels, and finally return to baseline values after 24h. This meta-analysis provides a better understanding of the acute endocrine response to a single HIIT session, which would certainly be valuable for both clinicians and coaches in the prescription of exercise programs to improve health and performance. Testosterone and cortisol may be used as sensitive biomarkers to monitor the anabolic and catabolic response to HIIT.

Acute Hormonal Responses to High-Intensity Interval Training in Hyperoxia.

This study aimed to compare selected hormonal responses to a single session of high intensity interval training performed with an increased fraction of inspired oxygen (hyperoxia) and under normoxic conditions. Twelve recreationally trained men (age 24 ± 3 years) performed two sessions of high intensity interval training on a cycle ergometer, in randomized order with hyperoxia (4 L·min-1 with a flowrate of 94% O2) and normoxia. Each session consisted of 5 intervals of 3 minutes at 85% of the maximal power output, interspersed by 2 min at 40% of the maximal power output. Serum cortisol, prolactin and vascular endothelial growth factor (VEGF) were assessed both before and immediately after each high intensity interval training session. Statistically significant differences in cortisol were found between hyperoxic and normoxic conditions (p = 0.011), with a significant increase in hyperoxia (61.4 ± 73.2%, p = 0.013, ES = -1.03), but not in normoxia (-1.3 ± 33.5%, p > 0.05, ES = 0.1). Prolactin increased similarly in both hyperoxia (118.1 ± 145.1%, p = 0.019, ES = -0.99) and normoxia (62.14 ± 75.43%, p = 0.005, ES = -0.5). VEGF was not statistically altered in either of the conditions. Our findings indicate that a single session of high intensity interval training in low-dose hyperoxia significantly increased cortisol concentrations in recreationally trained individuals compared to normoxia, while the difference was smaller in prolactin and diminished in VEGF concentrations.

Acute Inflammatoru And Hormonal Response To Strength Training In Breast Cancer Survivors: A Preliminary Study

Acute Inflammatoru And Hormonal Response To Strength Training In Breast Cancer Survivors: A Preliminary Study

ACUTE ANDROGEN AND GLUCOCORTICOID RECEPTOR RESPONSE FOLLOWING A MODERATE INTENSITY RESISTANCE EXERCISE BOUT

PURPOSE: The purpose of this study was to examine the acute androgen receptor (AR) and glucocorticoid receptor (GR) response to a moderate intensity resistance exercise bout in resistance trained (RT) and untrained men (UT). METHODS: RT men (n = 10; X ± SD, age = 21.3 ± 1.7 yrs, height = 175.8 ± 6.8 cm, body mass = 84.5 ± 13.5 kg, back squat 1RM = 154.3 ± 19.3 kg, training history = 5.4 ± 2.0 yrs) and UT men (n = 9; X ± SD, age = 20.8 ± 3.1 yrs, height = 178.7 ± 8.9 cm, body mass = 81.0 ± 14.0 kg, squat 1RM = 108.1 ± 13.7 kg, training history = 0.7 ± 1.7 yrs) volunteered for this study. Prior to the RE bout, subjects were strength tested for back squat (BS) and leg extension (LE). Subjects returned 4-7 days later between 10am-2pm, and completed a RE bout consisting of 6 sets of 10 repetitions of BS at 75% 1RM, immediately followed by 4 sets of 10 repetitions of LE at 75% 1RM with 1.5 min rest between all sets. Muscle samples were collected from the vastus lateralis prior to exercise (PRE) and 10 min (10P), 30 min (30P), 60 min (60P), and 180 min (180P) post exercise. Total AR and GR expression was determined via western blotting. Receptor data were not normally distributed, thus all receptor data were analyzed using Mann-Whitney U test, Friedman test, and Wilcoxon signed-rank test. RESULTS: For total AR expression, there were no differences between time points within the RT group (p > .05); however, there were differences between time points within the UT group (p = .016). In the UT group, total AR expression significantly decreased at 30P (-19%∆, z = -2.192, p = .027) and 60P (-11%∆, z = -2.192, p = .027) post exercise, but returned to baseline values by 180P (z = -.178, p > .05). For Total GR content, there were no differences between time points within the RT or UT groups (p > .05). Total GR content was significantly greater in the RT group compared to the UT group at 10P (Mann-Whitney U = 19, z = -2.123, p = .035). CONCLUSIONS: While no changes were observed for AR expression in the RT group, the UT subjects experienced a significant decrease in AR expression at 30P and 60P suggesting acute AR responses vary depending on training status. No differences were seen across time for the GR in either group; however, RT and UT subjects were different from each other at 10P. It is unclear if these responses are related to the acute hormonal response; therefore, future research will address this.

Acute Hormone Responses Subsequent to Agonist-Antagonist Paired Set vs. Traditional Straight Set Resistance Training

Miranda, H, de Souza, JAAA, Scudese, E, Paz, GA, Salerno, VP, Vigário, PdS, and Willardson, JM. Acute hormone responses subsequent to agonist-antagonist paired set vs. traditional straight set resistance training. J Strength Cond Res 34(6): 1591-1599, 2020-The purpose of this study was to compare acute hormone responses and rating of perceived exertion (OMNI-Res) subsequent to the agonist-antagonist paired set (PS) vs. the traditional straight set (TS) resistance training method. Twelve recreationally trained men (25.7 ± 4.7 years, 173 ± 6.3 cm and 71.5 ± 6.6 kg) participated in the current study. After 10 repetition maximum (RM) load determination, each subject performed the following 2 experimental sessions in random order: TS session-3 sets of 10 repetitions at 85% of 10RM for the machine seated row and barbell bench press with 2-minute rest intervals between sets; and PS-3 sets of 10 repetitions with 85% of 10RM alternating machine seated row and barbell bench press for the total of 6 PSs with 2-minute rest intervals between sets. Total testosterone (TT), free testosterone (FT), cortisol, TT/cortisol ratio, growth hormone (GH), and blood lactate concentrations were measured before workout and immediately after workout and 15 and 30 minutes after workout. The OMNI-RES was recorded at the end of each set for both exercises within each session. Under the TS session, TT significantly increased immediately post-workout vs. the pre-workout time point. For the PS session, TT significantly decreased at 30-minute post-workout vs. the immediate post-workout time point, whereas, FT significantly increased immediately post-workout and 15-minute post-workout vs. the pre-workout time point. For the TS session, GH significantly increased immediately post-workout, and at the 15- and 30-minute post-workout time points vs. the pre-workout time point, respectively. For the PS session, GH was significantly increased immediately post-workout vs. the pre-workout time point. Blood lactate significantly increased at all post-workout time points vs. the pre-workout time point under both sessions. The cortisol and TT/cortisol ratio showed no differences between sessions. In conclusion, from an acute standpoint, the TS approach showed a tendency to cause greater disruption in hormone levels, despite the lack of significant differences vs. the PS approach at all time points. However, both strategies may promote similar acute hormone responses.

Whey protein isolate or concentrate combined with concurrent training does not augment performance, cardiorespiratory fitness, or strength adaptations.

Protein supplementation alters both strength and endurance training adaptations individually; however less is known regarding protein supplementation during concurrent training. The primary purpose of this study was to investigate the effects of whey protein supplementation during six weeks of concurrent training on performance, cardiorespiratory fitness, and maximal strength adaptations, as well as acute hormonal and immune responses. A secondary purpose was to explore the effects of two types of whey protein powders on these latter variables. Thirty-one participants were randomly assigned to supplement with a placebo (PLA; N.=10), whey protein isolate (WPI; N.=10), or whey protein concentrate (WPC; N.=11) in addition to their habitual diet. Total protein intake was 1.2, 3.5, and 3.5 g/kg/day for PLA, WPI, WPC groups, respectively. Exercise testing was performed before and after 6 weeks of concurrent training. Blood samples were obtained at rest, and 5 and 60 minutes after a simulated 2000 m rowing race prior to and after training. There were similar but significant improvements in cardiorespiratory fitness (PLA +7.5%; WPI +3.9%; WPC +6.9%), upper body strength (PLA +5.5%; WPI +5.1%; WPC +6.7%), lower body strength (PLA +13.6%; WPI +9.4%; WPC +14.1%) and 2000m rowing performance (PLA -2.5%; WPI -2.3%; WPC -2.3%) in all groups, P<0.05. As well, hormonal and immune responses to acute exercise were similar over time and between groups. Whey protein supplementation did not differentially influence performance, cardiorespiratory fitness, upper and lower body strength, immune or hormonal adaptations following 6 weeks of concurrent training.

Acute Neuromuscular and Endocrine Responses to Two Different Compound Exercises: Squat vs. Deadlift.

Barnes, MJ, Miller, A, Reeve, D, and Stewart, RJ. Acute neuromuscular and endocrine responses to two different compound exercises: squat vs. deadlift. J Strength Cond Res 33(9): 2381-2387, 2019-Anecdotally, it is believed that the deadlift exercise brings about greater levels of central fatigue than other exercises; however, no empirical evidence exists to support this view. In addition, little is known about the acute endocrine response to heavy deadlift exercise and how this may differ from other similar compound exercises. Therefore, the aim of this study was to identify and compare the acute, neuromuscular and endocrine responses to squat and deadlift exercises. Ten resistance-trained males completed 8 sets of 2 repetitions at 95% of 1 repetition maximum. Maximum voluntary isometric contraction (MVIC) force of the quadriceps, along with measures of central (voluntary activation [VA] and surface electromyography) and peripheral (electrically evoked control stimulus) fatigue were made before and 5 and 30 minutes after exercise. In addition, salivary testosterone and cortisol were measured at these same time points. MVIC was reduced after the completion of both exercises (p = 0.007); however, no difference between exercises was evident. Similarly, although VA changed over time (p = 0.0001), no difference was observed between exercises. As a measure of peripheral fatigue, force from the control stimulus changed over time (p = 0.003) with a greater decrease evident after the squat (p = 0.034). Electromyography was reduced over time (p = 0.048) but no difference was seen between exercises. No change was seen in testosterone and cortisol. Although a greater absolute load and larger volume load were completed for the deadlift, no difference in central fatigue was evident between the 2 compound exercises. The greater peripheral fatigue observed after squat exercise may be due to the greater work completed by the quadriceps with this exercise. These results suggest that separate periodization, tapering, and programming considerations may be unnecessary when using the squat and deadlift to develop muscular strength.

Whole-Body Cryotherapy: Potential to Enhance Athlete Preparation for Competition?

The final hours of preparation before competition are important for performance. Recovery, preparation and warm up protocols are evolving continuously and include passive and active modalities often developed by “trial and error” approaches. Passive modalities, such as whole-body cryotherapy (WBC), have the potential to enhance both recovery and preparation. Whole-body cryotherapy has generally been used within a recovery setting after competition or strenuous training for athletes, and in clinical settings for the general population. However, the acute hormonal, anti-inflammatory, perceptual and psychological responses yielded by a single, or repeated, bouts of WBC indicate that this practice could enhance an athlete’s competition readiness when used alongside traditional elements of active warm-ups in the hours before competition in addition to aiding recovery in the hours after. Here we summarize and evaluate the acute effects of WBC exposures on physiological, performance and perceptual responses, and examine the likelihood these responses could theoretically translate into enhanced athletic performance. The potential to enhance an athlete’s performance using acute passive WBC exposure is a novel intervention that requires further investigation.

Salivary testosterone and cortisol concentrations after two different resistance training exercises.

The aim of this study was to identify the acute hormonal responses of salivary testosterone (T) and cortisol (C) concentrations during and after two different resistance exercises involving the lower and the upper body, respectively. For this reason, 13 healthy recreationally trained male athletes performed an identical strength protocol (5x10 reps, with ~75% of 1 RM) with the exercises bench press and back-squat in a cross-over design. Saliva samples were taken at baseline (t0), mid training (t1), immediately after (t2), 15 (t3) and 45 minutes after the training (t4). Samples were analyzed for T and C, and the T/C ratio was calculated. T concentrations increased significantly from t0 to t2, t3 and t4 and also at t3 and t4 for C in the back-squat protocol (P<0.05). There were no significant changes for T and C in the bench press protocol (P<0.05). The T/C ratio remained constant for the bench press protocol. The T/C ratio increased in the squat protocol at t2 and decreased at t3 and t4. We conclude that back-squat exercise can change the hormonal state of the body after an intense resistance training workout, while an exercise with a lower amount of muscle mass (i.e. bench press) has almost no influence on T and C.