High-Intensity Interval Training Decreases Muscle Sympathetic Nerve Activity in Men With Essential Hypertension and in Normotensive Controls.

Exercise training is a cornerstone in reducing blood pressure (BP) and muscle sympathetic nerve activity (MSNA) in individuals with essential hypertension. High-intensity interval training (HIIT) has been shown to be a time efficient alternative to classical continuous training in lowering BP in essential hypertension, but the effect of HIIT on MSNA levels has never been investigated. Leg MSNA responsiveness to 6 weeks of HIIT was examined in 14 hypertensive men (HYP; age: 62 ± 7 years, night time BP: 136 ± 12/83 ± 8 mmHg, BMI: 28 ± 3 kg/m2), and 10 age-matched normotensive controls (NORM; age: 60 ± 8 years, night time BP: 116 ± 2/68 ± 4 mmHg and BMI: 27 ± 3 kg/m2). Before training, MSNA levels were not different between HYP and NORM (burst frequency (BF): 41.0 ± 10.3 vs. 33.6 ± 10.6 bursts/min and burst incidence (BI): 67.5 ± 19.7 vs. 64.2 ± 17.0 bursts/100 heart beats, respectively). BF decreased (P < 0.05) with training by 13 and 5% in HYP and NORM, respectively, whereas BI decreased by 7% in NORM only, with no difference between groups. Training lowered (P < 0.05) night-time mean arterial- and diastolic BP in HYP only (100 ± 8 vs. 97 ± 5, and 82 ± 6 vs. 79 ± 5 mmHg, respectively). The change in HYP was greater (P < 0.05) compared to NORM. Training reduced (P < 0.05) body mass, visceral fat mass, and fat percentage similarly within- and between groups, with no change in fat free mass. Training increased (P < 0.05) V̇O2-max in NORM only. Six weeks of HIIT lowered resting MSNA levels in age-matched hyper- and normotensive men, which was paralleled by a significant reduction in BP in the hypertensive men.

Effect of additional speed endurance training on performance and muscle adaptations.

PURPOSE: The present study examined the effect of additional speed endurance training (SET) during the season on muscle adaptations and performance of trained soccer players. METHODS: Eighteen subelite soccer players performed one session with six to nine 30-s intervals at an intensity of 90%-95% of maximal intensity (SET) a week for 5 wk (SET intervention). Before and after the SET intervention, the players carried out the Yo-Yo intermittent recovery level 2 (Yo-Yo IR2) test, a sprint test (10 and 30 m), and an agility test. In addition, seven of the players had a resting muscle biopsy specimen taken and they carried out a running protocol on a motorized treadmill before and after the SET intervention. RESULTS: After the SET intervention, the Yo-Yo IR2 test (n = 13) performance was 11% better (P < 0.05), whereas sprint (n = 15) and agility (n = 13) performances were unchanged. The expression of the monocarboxylate transporter 1 (n = 6) was 9% higher (P < 0.05). and the expression of the Na(+)/K(+) pump subunit ß(1) (n = 6) was 13% lower (P < 0.05) after the SET intervention. The Na(+)/K(+) pump subunits α(1), α(2), as well as the monocarboxylate transporter 4 and the Na(+)/H(+) exchanger 1 (n = 6) were unchanged. After the SET intervention, the relative number of Type IIx fibers and oxygen consumption at 10 km.h(-1) were lower (P < 0.05), whereas VO(2max) was unchanged. CONCLUSIONS: In conclusion, adding ∼30 min of SET once a week during the season for trained soccer players did lead to an improved ability to perform repeated high-intensity exercise, with a concomitant increase in the expression of monocarboxylate transporter 1 and an improved running economy.