Sprint Interval Training Attenuates Neuromuscular Function and Vagal Reactivity Compared With High-Intensity Functional Training in Real-World Circumstances.

ABSTRACT: Benítez-Flores, S, de S. Castro, FA, Lusa Cadore, E, and Astorino, TA. Sprint interval training attenuates neuromuscular function and vagal reactivity compared with high-intensity functional training in real-world circumstances. J Strength Cond Res 37(5): 1070-1078, 2023-The aim of this study was to compare the acute cardiovascular and neuromuscular effects of 3 time-matched sessions of high-intensity training. Eighteen moderately active adults (9 women and 9 men [age: 23 ± 2.9 years; maximum oxygen consumption (V̇ o2 max): 47.6 ± 4.1 ml·kg -1 ·min -1 ]) performed three low-volume (∼9 minutes) sessions in a randomized order: sprint interval training (SIT), burpee interval training (BIT) (10 × 5 seconds efforts × 35 seconds recovery), and vigorous intensity continuous training (VICT) (6 minutes 5 seconds of running at ∼85% of peak heart rate [HR peak ]). Indices related to heart rate (HR), neuromuscular performance (counter movement jump height [CMJ height ] and squat and bench press power), and autonomic balance (heart rate recovery and heart rate variability [HRR and HRV] )were monitored during exercise. Sprint interval training and VICT elicited a higher HR mean (171.3 ± 8.4 and 166.5 ± 7.5 vs. 150.5 ± 13.6 b·min -1 , p < 0.001) and time of ≥90%HR peak (133.3 ± 117.4 and 110 ± 128.9 vs. 10 ± 42.4 seconds, p < 0.01) than BIT. Sprint interval training exhibited a slower HRR and lower HRV than BIT and VICT ( p < 0.05) postsession. Moreover, only SIT resulted in a significant decline ( p < 0.01) in CMJ height (34.7 ± 7.2 to 33.5 ± 7.2 cm), relative squat mean power (25.5 ± 4.5 to 23.8 ± 4.9 W·kg -1 ), and relative bench press peak power (6.9 ± 2.4 to 6.2 ± 2.5 W·kg -1 ). Results revealed that SIT diminishes the sympathovagal reactivation and neuromuscular performance compared with work-matched BIT and VICT.

Effects of Combined Resistance and Power Training on Cognitive Function in Older Women: A Randomized Controlled Trial.

The present study compared the effects of traditional resistance training (TRT) and combined power training (PT) and TRT (PTRT) on cognitive parameters and serum brain-derived neurotrophic factor (BDNF) levels in non-demented, well-functioning, community-dwelling older women. Forty-five older women were randomized into one of three experimental groups: TRT, PTRT, and control group (CG). Cognitive tests explored global cognitive function, short-term memory, and dual-task performance. Serum BDNF levels were assessed at baseline and after the intervention. Exercise sessions were performed twice a week over 22 weeks. In TRT, exercise sessions were based on three sets of 8-10 repetitions at "difficult" intensity. In PTRT, the first session was based on PT (three sets of 8-10 repetitions at "moderate" intensity), while the second session was similar to the TRT. Our analyses indicated that overall cognitive function, short-term memory, and dual-task performance were similarly improved after TRT and PTRT. Serum BDNF concentrations were not altered by any training protocol. In conclusion, the two RT programs tested in the present trial improved global cognitive function, short-term memory and dual task performance in non-demented, well-functioning, community-dwelling older women. In addition, our findings suggest that mechanisms other than BDNF may be associated with such improvements.

The relation between force production at different hip angles and functional capacity in older women.

Although hip muscles are related to activities of daily living (ADLs) in older adults, there is a lack of evidence concerning the extensor-flexor hip torque-angle. A shift of the torque-angle relationship is caused by the aging process (increasing or reducing the range of motion) affecting the force production in a given muscular length during ADLs. Thus, the relationship between hip extensor-flexor muscles' force production and their association with functional capacity tests in elderly women were evaluated. Seventeen elderly women performed timed up and go, timed up and down stairs, and 30-s chair stand tests. Hip extensor-flexor isometric peak torques at 15°, 60°, 90°, and 100° (0°â€¯= full extension) were also assessed. Hip flexors produced the highest absolute and relative peak torque at a 15° angle and hip extensor muscles at 100°. A large and significant correlation (r = 0.62, p = 0.008) was observed only between absolute hip extensor peak torque at 90° and the 30-s chair stand test. When peak torque was normalized by body mass, the hip extensor-flexor muscles' peak torque obtained at all measured angles presented significant correlation with the 30-s chair stand test. The results indicate that for older women there is an optimum torque-angle for the hip flexor and extensor muscles. Furthermore, although the hip torque-angle relationship was measured under isometric contractions, there was a correlation with the 30-s chair stand test, which could indicate the presence of the isometric component during this movement.

Preventing metabolic syndrome in morbid obesity with resistance training: Reporting interindividual variability.

BACKGROUND AND AIMS: Resistant training (RT) improves health markers in obesity, but its effects in morbid obesity are unknown. We aimed to determine the effects of a RT-program in preventing/attenuating the metabolic syndrome (MetS) in patients with morbid obesity. A second aim was to report the interindividual variability in terms of improvements in MetS markers and other related co-variables. METHODS AND RESULTS: Twenty-one adults with obesity or morbid obesity were divided into two groups based on body mass index (BMI): a control obesity (CO, n = 7, BMI ≥35 < 40.0 kg/m2) and a morbid obese group (MO, n = 14, BMI ≥40 kg/m2). Participants completed a 20-week RT-program (3 sessions/week, 4-8 exercise) using free weights. Participants were assessed for MetS markers (waist circumference, systolic and diastolic blood pressure [BP], fasting glucose, high-density lipoproteins, and triglycerides) and other co-variables (total cholesterol, low-density lipoprotein, one-maximum repetition of biceps curl, and handgrip strength, 6 min walking test). Significant reductions in MetS markers were observed in both CO and MO groups (P < 0.05 to P < 0.0001), but significant reductions in diastolic BP and increases in HDL-C were noted only in the MO group (P < 0.0001). Changes in waist circumference, and systolic and diastolic BP were significantly greater only in the MO group (P < 0.001), but the CO group presented a greater fasting glucose decreases (P < 0.0001). The prevalence of non-responders between CO and MO groups was similar in the MetS outcomes. CONCLUSIONS: RT promotes greater improvements in overall MetS outcomes waist circumference, BP, and plasma triglycerides in patients with morbid obesity than in obese peers, with no overall differences in the prevalence of non-responders. CLINICAL TRIAL NUMBER: NCT03921853 at www.clinicaltrials.gov.

Muscle conduction velocity, surface electromyography variables, and echo intensity during concentric and eccentric fatigue.

INTRODUCTION: Concentric (CON) and eccentric (ECC) contractions may involve different mechanisms related to changes in sarcolemma status and the consequent alteration of action potential transmission along muscle fibers. METHODS: Muscle conduction velocity (CV), surface electromyography signal (sEMG), muscle quality, and blood lactate concentrations were analyzed during CON and ECC actions. RESULTS: Compared with ECC, the CON protocol resulted in greater muscle force losses, blood lactate concentrations, and changes in sEMG parameters. Similar reductions in CV were detected in both protocols. Higher echo intensity values were observed 2 days after ECC due to greater muscle damage. CONCLUSIONS: The effects of the muscle damage produced by ECC exercise on the transmission of action potentials along muscle fibers (measured as the CV) may be comparable with the effects of hydrogen accumulation produced by CON exercise (related to greater lactate concentrations), which causes greater force loss and change in other sEMG variables during CON than during ECC actions.