Time Course of Neuromuscular Fatigue During Different Resistance Exercise Loadings in Power Athletes, Strength Athletes, and Nonathletes

ABSTRACT

Kotikangas, J, Walker, S, Peltonen, H, and Häkkinen, K. Time course of neuromuscular fatigue during different resistance exercise loadings in power athletes, strength athletes, and nonathletes. J Strength Cond Res 38(7): 1231-1242, 2024-Training background may affect the progression of fatigue and neuromuscular strategies to compensate for fatigue during resistance exercises. Thus, our aim was to examine how training background affects the time course of neuromuscular fatigue in response to different resistance exercises. Power athletes (PA, n = 8), strength athletes (SA, n = 8), and nonathletes (NA, n = 7) performed hypertrophic loading (HL, 5 × 10 × 10RM), maximal strength loadings (MSL, 7 × 3 × 3RM) and power loadings (PL, 7 × 6 × 50% of 1 repetition maximum) in back squat. Average power (AP), average velocity (VEL), surface electromyography (sEMG) amplitude (sEMGRMS), and sEMG mean power frequency (sEMGMPF) were measured within all loading sets. During PL, greater decreases in AP occurred from the beginning of SET1 to SET7 and in VEL to both SET4 and SET7 in NA compared with SA (p < 0.01, g > 1.84). During HL, there were various significant group × repetition interactions in AP within and between sets (p < 0.05, ηp2 > 0.307), but post hoc tests did not indicate significant differences between the groups (p > 0.05, g = 0.01-0.93). During MSL and HL, significant within-set and between-set decreases occurred in AP (p < 0.001, ηp2 > 0.701) and VEL (p < 0.001, ηp2 > 0.748) concurrently with increases in sEMGRMS (p < 0.01, ηp2 > 0.323) and decreases in sEMGMPF (p < 0.01, ηp2 > 0.242) in all groups. In conclusion, SA showed fatigue resistance by maintaining higher AP and VEL throughout PL. During HL, PA tended to have the greatest initial fatigue response in AP, but between-group comparisons were nonsignificant despite large effect sizes (g > 0.8). The differences in the progression of neuromuscular fatigue may be related to differing neural activation strategies between the groups, but further research confirmation is required.

Periodization and Block Periodization in Sports: Emphasis on Strength-Power Training-A Provocative and Challenging Narrative

ABSTRACT

Stone, MH, Hornsby, WG, Haff, GG, Fry, AC, Suarez, DG, Liu, J, Gonzalez-Rave, JM, and Pierce, KC. Periodization and block periodization in sports: emphasis on strength-power training-a provocative and challenging narrative. J Strength Cond Res 35(8): 2351-2371, 2021-Periodization can be defined as a logical sequential, phasic method of manipulating fitness and recovery phases to increase the potential for achieving specific performance goals while minimizing the potential for nonfunctional over-reaching, overtraining, and injury. Periodization deals with the micromanagement of timelines and fitness phases and is cyclic in nature. On the other hand, programming deals with the micromanagement of the training process and deals with exercise selection, volume, intensity, etc. Evidence indicates that a periodized training process coupled with appropriate programming can produce superior athletic enhancement compared with nonperiodized process. There are 2 models of periodization, traditional and block. Traditional can take different forms (i.e., reverse). Block periodization has 2 subtypes, single goal or factor (individual sports) and multiple goals or factors (team sports). Both models have strengths and weaknesses but can be "tailored" through creative programming to produce excellent results for specific sports.

Vitamin D supplementation does not enhance resistance training-induced gains in muscle strength and lean body mass in vitamin D deficient young men

PURPOSE

Vitamin D (Vit-D) supplementation has been shown to increased muscle strength in young adults. It remains unclear if Vit-D supplementation enhances the efficacy of resistance training (RT). This study tested the hypothesis that Vit-D supplementation would enhance the RT-induced increases in muscle strength and lean body mass (LBM) in Vit-D deficient young men.

METHODS

Thirty-nine men (baseline serum 25(OH)D < 50 nmol L^‒1) were quasi-randomly assigned to one of the two groups that performed a 12-week supervised RT program concomitant with either Vit-D (8000 IU daily; VD) or placebo (PLC) supplementation.

RESULTS

During 12-week RT, energy and nutrient (except Vit-D) intake and training loads did not differ in the two groups. Serum 25(OH)D levels increased from 36.3 ± 9.2 to 142.4 ± 21.9 nmol L^‒1 (P < 0.05) in VD group and remained unchanged between 36.3 ± 8.9 and 29.4 ± 6.6 nmol L^‒1 (P > 0.05) in PLC group. Muscle strength (1-repetition maximum) increased (P < 0.05) to an equal extent in the two groups in 5 exercises performed on RT equipment, whereas strength gains in chest press and seated row were greater (P < 0.05) in PLC compared to VD group. Total and regional LBM (measured by DXA scan) increased (P < 0.05) equally in the two groups. Android fat mass decreased (P < 0.05) in VD group only.

CONCLUSION

Vit-D supplementation does not enhance the efficacy of RT in terms of muscle strength and LBM gains in Vit-D deficient young healthy men.

Contrast Tempo of Movement and Its Effect on Power Output and Bar Velocity During Resistance Exercise

In this study, we examined the impact of contrast movement tempo (fast vs. slow) on power output and bar velocity during the bench press exercise. Ten healthy men (age = 26.9 ± 4.1 years; body mass = 90.5 ± 10.3 kg; bench press 1RM = 136.8 ± 27.7 kg) with significant experience in resistance training (9.4 ± 5.6 years) performed the bench press exercise under three conditions: with an explosive tempo of movement in each of three repetitions (E/E/E = explosive, explosive, explosive); with a slow tempo of movement in the first repetition and an explosive tempo in the next two repetitions (S/E/E = slow, explosive, explosive); and with a slow tempo of movement in the first two repetitions and an explosive tempo in the last repetition (S/S/E = slow, slow, explosive). The slow repetitions were performed with a 5/0/5/0 (eccentric/isometric/concentric/isometric) movement tempo, while the explosive repetitions were performed with an X/0/X/0 (X- maximal speed of movement) movement tempo. During each experimental session, the participants performed one set of three repetitions at 60%1RM. The two-way repeated measures ANOVA showed a statistically significant interaction effect for peak power output (PP; p = 0.03; η² = 0.26) and for peak bar velocity (PV; p = 0.04; η² = 0.24). Futhermore there was a statistically significant main effect of condition for PP (p = 0.04; η² = 0.30) and PV (p = 0.02; η² = 0.35). The post hoc analysis for interaction revealed that PP was significantly higher in the 2nd and 3rd repetition for E/E/E compared with the S/S/E (p < 0.01 for both) and significantly higher in the 2nd repetition for the S/E/E compared with S/S/E (p < 0.01). The post hoc analysis for interaction revealed that PV was significantly higher in the 2nd and 3rd repetition for E/E/E compared with the S/S/E (p < 0.01 for both), and significantly higher in the 2nd repetition for the S/E/E compared with the S/S/E (p < 0.01). The post hoc analysis for main effect of condition revealed that PP and PV was significantly higher for the E/E/E compared to the S/S/E (p = 0.04; p = 0.02; respectively). The main finding of this study was that different distribution of movement tempo during a set has a significant impact on power output and bar velocity in the bench press exercise at 60%1RM. However, the use of one slow repetition at the beginning of a set does not decrease the level of power output in the third repetition of that set.

Hunger is suppressed after resistance exercise with moderate-load compared to high-load resistance exercise: the potential influence of metabolic and autonomic parameters

The purpose of present study was to compare the effects of moderate-load versus high-load resistance exercise (RE) on hunger response, blood lactate, glucose, and autonomic modulation in trained men, and to examine the correlations between these parameters. For this, 11 recreationally resistance-trained males performed 2 randomized trials: moderate-load (6 sets at 70% 1-repetition maximum (1RM) and a 90-s rest interval between sets) and high-load (6 sets at 90% 1RM and a 180-s rest interval between sets) leg-press exercise until movement failure. The subjective rating of hunger was obtained through a visual analog scale. Glucose and lactate concentration were evaluated at rest, immediately after exercise, and 30 min after exercise. Heart rate variability was recorded at baseline and during recovery (until 30 min after exercise) to assess autonomic modulation. The moderate-load condition induced lower subjective hunger ratings than the strength condition immediately after exercise (19.7 ± 16.6 vs 47.3 ± 27.7 mm), 30 min after exercise (33.6 ± 22.9 vs 58.5 ± 29.9 mm), and 60 min after exercise (43.8 ± 26.6 vs 67.8 ± 27.9 mm) (p < 0.05) and lower area under the curve hunger in relation to the high-load condition (p < 0.006). Moderate-load RE presented greater lactate concentration and induced slower heart rate variability recovery in relation to high-load RE (p < 0.05), but no difference was found in glucose, as well as no correlations between any of the variables investigated. In conclusion, moderate-load RE induced lower subjective hunger ratings, slower recovery of the parasympathetic nervous system, and higher lactate concentration in relation to high-load RE, but the metabolic variables were not correlated with hunger suppression.