Endocrine responses following exhaustive strength exercise with and without the use of protein and protein-carbohydrate supplements

Recovery during Successive 120-min Football Games: Results from the 120-min Placebo/Carbohydrate Randomized Controlled Trial

PURPOSE

This study aimed to examine the recovery kinetics (i.e., time-dependent changes) of performance-related variables between two 120-min male football games performed 3 d apart with and without carbohydrate supplementation.

METHODS

Twenty male players (20 ± 1 yr; body fat, 14.9% ± 5.1%; maximal oxygen consumption, 59.4 ± 3.7 mL·kg -1 ·min -1 ) participated in two 120-min football games (G1, G2) according to a randomized, two-trial, repeated-measures, crossover, double-blind design. Participants received carbohydrate/placebo supplements during recovery between games. Field activity was monitored during the games. Performance testing and blood sampling were performed before and at 90 and 120 min of each game. Muscle biopsies were collected at baseline and at 90 and 120 min of G1 and pre-G2.

RESULTS

Compared with G1, G2 was associated with reduced total distance (10,870 vs 10,685 m during 90 min and 3327 vs 3089 m during extra 30 min; P = 0.007-0.038), average (6.7 vs 6.2 km/h during extra 30-min game-play; P = 0.007) and maximal speed (32.2 vs 30.2 km/h during 90 min and 29.0 vs 27.9 km/h during extra 30 min; P < 0.05), accelerations/decelerations ( P < 0.05), and mean heart rate ( P < 0.05). Repeated sprint ability ( P < 0.001), jumping ( P < 0.05), and strength ( P < 0.001) performance were compromised before and during G2. Muscle glycogen was not restored at G2 baseline ( P = 0.005). Extended game-play reduced lymphocyte, erythrocyte counts, hematocrit, hemoglobin, reduced glutathione ( P < 0.05) and increased delayed onset of muscle soreness, creatine kinase activity, blood glycerol, ammonia, and protein carbonyls ( P < 0.05) before and during G2. Pax7 + ( P = 0.004) and MyoD + cells ( P = 0.019) increased at baseline G2. Carbohydrate supplementation restored performance and glycogen, reduced glycerol and delayed onset of muscle soreness responses, and increased leukocyte counts and Pax7 + and MyoD + cells.

CONCLUSIONS

Results suggest that extended football games induce a prolonged recovery of performance, which may be facilitated by carbohydrate supplementation during a congested game fixture.

Ischemia during rest intervals between sets prevents decreases in fatigue during the explosive squat exercise: a randomized, crossover study

The study aimed to evaluate the impact of ischemia, used only before particular sets of a lower limb resistance exercise on power output. Ten healthy resistance-trained males (age = 26 ± 6 years; body mass = 90 ± 9 kg; training experience = 9 ± 7 years) performed two experimental sessions (with ischemia; control without ischemia) following a randomized crossover design. During the ischemic condition, the cuffs were inflated to 60% of arterial occlusion pressure. The cuffs were applied before each set for 4.5 min and released 30 s before the start of the set as the reperfusion (4.5 min ischemia + 0.5 min reperfusion). In the control condition, ischemia was not applied. During the experimental sessions, the subjects performed the Keiser machine squat exercise protocol which consisted of 5 sets of two repetitions, at a load of 60% of one-repetition maximum (1RM), with 5 min rest intervals between sets. The repetitions were performed with maximal velocity. The two-way repeated-measures ANOVA showed a statistically significant interaction effect for power output (p < 0.01; η² = 0.26). There was also a statistically significant main effect of condition for power output (p = 0.02; η² = 0.40). The post hoc analysis for interaction did not show significant differences between conditions in particular sets. The post hoc analysis for the main effect of the condition revealed that power output was significantly lower in the control group compared to the group where ischemic was used (p = 0.02). The t-test comparisons for particular sets showed a significant lower power output in set 3 (p = 0.03); set 4 (p < 0.01) and set 5 (p < 0.01) for the control condition when compared to the ischemic condition. The results indicate that ischemia applied before each set and released 30 s prior to the start of the squat exercise did not increase power output performance. However, we observed a significantly lower decline in power for the ischemic condition (4.5 min ischemia + 0.5 min reperfusion) in sets 3–5 compared to the control condition. Thus repeated ischemia with reperfusion used between sets can be an effective form of performance enhancement by preventing or at least diminishing fatigue during resistance exercise.

Effect of a Shock Micro-Cycle on Biochemical Markers in University Soccer Players

This study aimed to examine various biochemical biomarkers changes during a shock micro-cycle in soccer players from a university team. The study had 22 players (age: 22 ± 3 years; body mass: 68.6 ± 7.1 kg; height: 1.73 ± 0.07 m). The study measured total cholesterol (TC), triglycerides (TG), cholesterol linked to high-density lipoproteins (HDL), low-density lipoproteins (LDL), very low density lipoproteins (VLDL), arterial index (AI), creatine kinase (CK), glutamate-oxalacetate-transaminase (GOT), glutamate-pyruvate-transaminase (GPT), creatinine (Cr), catalase (CAT), superoxide dismutase (SOD), cytokines IL6 and TNFα, total antioxidant capacity (Cap antiox tot), hemolysis percentage and glomerular filtration rate (GFR); measurements were conducted during a shock micro-cycle. The lipid profile variables had no statistical significance when compared on day 1 with day 14. Except for TNFα, the other biomarkers compared with day one had progressive increments until day seven, with a subsequent reduction on day 14; however, none of the biomarkers returned to baseline values despite this decrease. The data shown herein suggest the need to research these biomarkers in distinct types of mesocycles, exercise, intensity, load, and duration to diminish fatigue and improve athlete performance.

Transfer of Dry-Land Resistance Training Modalities to Swimming Performance

A great number of studies focusing on the effects of dry-land resistance training interventions on swimming performance remain inconclusive. It is suggested that transferability of dry-land strength gains to swimming performance appear when dry-land resistance training programs are swim-specific. The main aim of this study was to compare the effects of specific dry-land resistance training on an ergometer with traditional dry-land exercises, and to determine how much of the resistance training effects were transferred to specific swimming conditions. The study included a group of 26 youth competitive male swimmers (age 15.7 ± 0.5 years, height 174.6 ± 6.6 cm, weight 68.4 ± 8.2 kg, training experience 5.8±0.7 years) of regional level. They were randomly allocated to one of two groups: experimental (E) and control (T). Both groups were involved in a 12-week dry-land resistance training concentrated on increasing muscular strength and power output of the upper limbs. Group E used a specialized ergometer (JBA – Zbigniew Staniak), while group T performed traditional resistance exercises. The program consisted of 10 sets of 30 s of exercise with 30 s rest intervals between each set. A two-way repeated measures ANOVA with Tukey HSD post hoc comparisons was used to determine if any significant differences existed between training groups across pretest and posttest conditions. The significance level was set at p ≤ 0.05. Dry-land resistance training modalities were the only differences in training between both groups. Our findings show that rates of transfer are much higher in group E than in group T, which resulted in a significant increase in swimming velocity (by 4.32%, p<0.001; ES=1.23, and 2.78%, p<0.003, ES=0.31, respectively).

The influence of compressive gear on maximal load lifted in competitive powerlifting

The competition in powerlifting has been divided into two divisions, with gear equipment (EQ) and without gear equipment (RAW). When competing in the EQ division, additional supportive gear can be worn by the athletes, while in the RAW division such gear is not allowed. The aim of the study was to compare the results of the RAW and EQ powerlifting divisions based on the results of world championships and current world records. One-hundred and twenty powerlifters (63 men, 57 women) were included to the analysis. Post hoc analysis for the results of men’s world championships indicated significantly higher results of the barbell squat (SQ; p < 0.001; ES = 1.31), bench press (BP; p < 0.001; ES = 1.27) and deadlift (DL; p < 0.001; ES = 0.37) for EQ compared to the RAW division. Post hoc analysis for the results of women’s world championships indicated significantly higher results of the SQ (p < 0.001; ES = 1.31), BP (p < 0.001; ES = 1.13) and DL (p < 0.001; ES = 0.71) for the EQ compared to the RAW division. Post hoc analysis for men’s world record indicated significantly higher results in the SQ (p < 0.001; ES = 1.32) and BP (p < 0.001; ES = 1.24) for the EQ compared to the RAW division. Furthermore, there were no significant differences in the results of world records in the DL (p = 0.901; ES = 0.26) between the EQ and RAW divisions. Post hoc analysis for women’s world records indicated significantly higher results in the SQ (p < 0.001; ES = 1.22) and BP (p < 0.001; ES = 1.99) for the EQ compared to RAW division. The main finding of the study was that supportive gear increases maximal load lifted during powerlifting competition.

The Acute Impact of External Compression on Back Squat Performance in Competitive Athletes

The aim of the present study was to evaluate the effects of external compression with blood flow restriction on power output and bar velocity changes during the back-squat exercise (SQ). The study included 10 judo athletes (age = 28.4 ± 5.8 years; body mass = 81.3 ± 13.1 kg; SQ one-repetition maximum (1-RM) 152 ± 34 kg; training experience 10.7 ± 2.3 years). Methods: The experiment was performed following a randomized crossover design, where each participant performed three different exercise protocols: (1) control, without external compression (CONT); (2) intermittent external compression with pressure of 100% arterial occlusion pressure (AOP) (EC-100); and (3) intermittent external compression with pressure of 150% AOP (EC-150). To assess the differences between conditions, the participants performed 3 sets of 3 repetitions of the SQ at 70% 1-RM. The differences in peak power output (PP), mean power output (MP), peak bar velocity (PV), and mean bar velocity (MV) between the three conditions were examined using repeated measures two-way ANOVA. Results: The post hoc analysis for the main effect of conditions showed a significant increase in PP (p = 0.03), PV (p = 0.02), MP (p = 0.04), and MV (p = 0.03), for the EC-150, compared to the CONT. Furthermore, a statistically significant increase in PP (p = 0.04), PV (p = 0.03), MP (p = 0.02), and MV (p = 0.01) were observed for the EC-150 compared to EC-100. There were no significant changes in PP, PV, MP, and MV, between EC-100 and CONT conditions. Conclusion: The results indicate that the use of extremely high-pressure external compression (150% AOP) during high-loaded (70% 1-RM) lower limb resistance exercise elicits an acute increase in power output and bar velocity.

AMPD1 C34T Polymorphism (rs17602729) Is Not Associated with Post-Exercise Changes of Body Weight, Body Composition, and Biochemical Parameters in Caucasian Females

Background: The C34T polymorphism (rs 17602729) in adenosine monophosphate deaminase 1 gene (AMPD1) is associated with muscular energy metabolism in exercise. However, the role of its potential modifying impact on exercise-induced changes in obesity related parameters is unknown. The aim of the study was to determine if the C34T polymorphism influences the effects of an exercise training. Methods: This study examines a group of one hundred and sixty-eight, young, non-obese Caucasian women in Poland who took part in a 12-week aerobic training program to determine the impact of allele and genotype distribution on training outcomes. Results: A two-way analysis of variance ANOVA was conducted assuming a dominant model by pooling rare homozygotes and heterozygotes (TT + CT, n = 79) and comparing against common homozygotes (CC, n = 89). Our results showed that the AMPD1 C34T polymorphism was not related with selected parameters in study group. After completing the 12-week training program, a wide array of parameters (body mass, body mass index, fat mass, free fat mass, total body water) were significantly changed in the study participants with the exception of AMPD1 genotypes, among whom no significant changes were observed. Conclusions: The results did not confirm that harboring the rs 17602729 T allele influences the effects of the training program.

The Effects of Low-Energy Moderate-Carbohydrate (MCD) and Mixed (MixD) Diets on Serum Lipid Profiles and Body Composition in Middle-Aged Men: A Randomized Controlled Parallel-Group Clinical Trial

Carbohydrate-restricted diets have become very popular due to their numerous health benefits. The aim of this study was to determine the influence of 4 weeks of a well-planned, low-energy moderate-carbohydrate diet (MCD) and a low-energy mixed diet (MixD) on the lipoprotein profile, glucose and C-reactive protein concentrations, body mass, and body composition in middle-aged males. Sixty middle-aged males were randomly assigned to the following groups: hypocaloric MCD (32% carbohydrates, 28% proteins, and 40% fat), hypocaloric MixD (50% carbohydrates, 20% proteins, and 30% fat), and a conventional (control) diet (CD; 48% carbohydrates, 15% proteins, and 37% fat). The participants who were classified into the MCD and MixD groups consumed 20% fewer calories daily than the total daily energy expenditure (TDEE). Baseline and postintervention fasting triacylglycerol (TG), LDL (low-density lipoprotein) cholesterol (LDL-C), HDL (high-density lipoprotein) cholesterol (HDL-C), total cholesterol (tCh), glucose (Gl), and C-reactive protein were evaluated. Body mass (BM) and body composition changes, including body fat (BF), % body fat (PBF), and muscle mass (MM), were monitored. Compared with MixD and CD, MCD significantly changed the fasting serum concentrations of TG (p < 0.05), HDL-C (p < 0.05), LDL-C (p < 0.05), tCh (p < 0.05), and glucose (p < 0.01). Additionally, body fat content (kg and %) was significantly reduced (p < 0.05) after MCD compared with MixD and CD. After the MixD intervention, BM and MM decreased (p < 0.05) compared with baseline values. Compared with baseline, after the MixD, BM, MM, tCh, LDL-C, and TG changed significantly. The 4 week low-energy MCD intervention changed lipoproteins, glucose, and body fat to a greater extent than the low-energy MixD. A hypocaloric MCD may be suggested for middle-aged male subjects who want to lose weight by reducing body fat content without compromising muscle mass.

Mechanism of Action and the Effect of Beta-Hydroxy-Beta-Methylbutyrate (HMB) Supplementation on Different Types of Physical Performance - A Systematic Review

Beta-hydroxy-beta-methylbutyrate (HMB) has been used extensively as a dietary supplement for athletes and physically active people. HMB is a leucine metabolite, which is one of three branched chain amino acids. HMB plays multiple roles in the human body of which most important ones include protein metabolism, insulin activity and skeletal muscle hypertrophy. The ergogenic effects of HMB supplementation are related to the enhancement of sarcolemma integrity, inhibition of protein degradation (ubiquitin pathway), decreased cell apoptosis, increased protein synthesis (mTOR pathway), stimulation of the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis and enhancement of muscle stem cells proliferation and differentiation. HMB supplementation has been carried out with various groups of athletes. In endurance and martial arts athletes, HMB supplementation revealed positive effects on specific aerobic capacity variables. Positive results were also disclosed in resistance trained athletes, where changes in strength, body fat and muscle mass as well as anaerobic performance and power output were observed. The purpose of this review was to present the main mechanisms of HMB action, especially related to muscle protein synthesis and degradation, and ergogenic effects on different types of sports and physical activities.

The Acute Effect of Various Doses of Caffeine on Power Output and Velocity during the Bench Press Exercise among Athletes Habitually Using Caffeine

Background: Previously studies confirm ergogenic effects of caffeine (CAF); however there is no available scientific data regarding the influence of acute CAF intake on power output in athletes habitually consuming CAF. The main goal of this study was to assess the acute effect of 3, 6, 9 mg/kg/b.m. doses of CAF intake on power output and bench press bar velocity in athletes habitually consuming CAF. Methods: The study included 15 healthy strength-trained male athletes (age = 26.8 ± 6.2 years, body mass = 82.6 ± 9.7 kg; BMI = 24.8 ± 2.7; bench press 1RM = 122.3 ± 24.5 kg). All participants were habitual caffeine consumers (5.2 ± 1.2 mg/kg/b.m.; 426 ± 102 mg of caffeine per day). This study had a randomized, crossover, double-blind study design where each participant performed four different experimental sessions, with one week interval between each trial. In every experimental session participants performed bench press, three sets of five repetitions at 50% 1RM. The power output and bar velocity assessments under four different conditions: a placebo (PLAC), and three doses of caffeine ingestion: 3 mg/kg/b.m. (CAF-3), 6 mg/kg/b.m. (CAF-6) and 9 mg/kg/b.m. (CAF-9). Results: The statistical significance was set at p < 0.05. The repeated measures ANOVA between PLAC and CAF-3; CAF-6; CAF-9 revealed no statistically significant differences in power output and velocity of the bar during the bench press exercise. A large effect size (ES) in mean power-output was found between PLAC and CAF-9 in Sets 1 and 2. A large ES in peak power-output was found between PLAC and CAF-6 in Set 2, and between PLAC and CAF-9 in Sets 1 and 2. A large ES in peak velocity was found between PLAC and CAF-9 in Sets 1–3. Conclusion: The results of the present study indicate that acute doses of CAF before exercise does not have a significant effect on power output and bar velocity in a group of habitual caffeine users.

The acute effects of caffeine intake on time under tension and power generated during the bench press movement

BACKGROUND

The ability to generate high levels of power is one of the key factors determining success in many sport disciplines. Although there are studies confirming ergogenic effects of caffeine (CAF) on different physical and mental abilities, much controversy remains about its influence on power. The main goal of this study was to assess the effects of caffeine supplementation on time under tension (TUT) and the number of performed repetitions (REP). The second objective was to determine the effects of CAF supplementation on power (P) and movement velocity (V) during the bench press movement. Additionally the authors evaluated whether CAF has a significant effect on velocity of the bar in the eccentric (ECC) phase (VEMEAN) of the bench press movement.

METHODS

The study included 20 men (20-31 yrs., 87.3 ± 7.7 kg) with at least 2 years of experience in resistance training. The study participants were divided randomly into two groups: the supplemented group ingested caffeine before exercise (GCAF), while the control group was given a placebo (GCON). The exercise protocol consisted of performing the bench press movement with a load equal to 70%1RM with maximal possible velocity (X/0/X/0). The experimental sets were performed to momentary muscular failure.

RESULTS

The repeated measures ANOVA between the GCAF and GCON groups revealed statistically significant differences in 2 variables. Post-hoc tests demonstrated statistically significant differences in TUT when comparing the group supplemented with caffeine (13.689 s GCAF) to the one ingesting a placebo (15.332 s GCON) at p = 0.002. Significant differences were also observed in mean velocity during the eccentric phase of movement (0.690 m/s in the GCAF to 0.609 in GCON with p = 0.002). There were no significant differences in generated power and velocity in the CON phase of the movement between the GCAF and GCON. CONCLUSIONS: The main finding of the study is that CAF ingestion increases movement velocity of the bar in the eccentric phase of the movement, what results in shortening of the time under tension (TUT) needed for performing a specific number of repetitions, without decreasing power and velocity in the CON phase of the movement.

No Modification in Blood Lipoprotein Concentration but Changes in Body Composition after 4 Weeks of Low Carbohydrate Diet (LCD) Followed by 7 Days of Carbohydrate Loading in Basketball Players

Recently, low carbohydrate diets have become very popular due to their numerous health benefits. Unfortunately, little is known about their chronic effects on the blood lipid profile and other cardiovascular disease risk factors in athletic populations. We compared the results of a four week, well-planned low carbohydrate diet (LCD) followed by seven days of carbohydrate loading (Carbo-L) on fasting lipids - triacylglycerol's (TAG), LDL-C, HDL-C, total cholesterol (TCh), glucose, insulin and HOMA-IR levels in 11 competitive basketball players. During the experiment, we also measured body mass (BM) and body composition changes: body fat (BF), % of body fat (PBF), and fat free mass (FFM). Both diet procedures significantly changed the fasting serum concentration of TAG (p < 0.05) and body fat content (kg and %) (p < 0.05), without negative changes in FFM. The Carbo-L procedure increased (p < 0.05) fasting glucose levels significantly. A LCD may be suggested for athletes who want to reduce body mass and fat content without compromising muscle mass. Several weeks on a LCD does not change the lipoprotein - LDL-C and HDL-C level significantly, while a seven-day Carb-L procedure may increase body fat content and fasting glucose concentration. Such dietary procedures are recommended for team sport athletes to reduce fat mass, lipid profile disorders and insulin resistance.