The effect of eccentric strength training on heart rate and on its variability during isometric exercise in healthy older men

The purpose of this study was to determine the effect of muscle mass and the level of force on the contraction-induced rise in heart rate. We conducted an experimental study in a sample of 28 healthy men between 20 and 30 yr of age (power: 95%, α: 5%). Smokers, obese subjects, and those who performed regular physical activity over a certain amount of energetic expenditure were excluded from the study. The participants exerted two types of isometric contractions: handgrip and turning a 40-cm-diameter wheel. Both were sustained to exhaustion at 20 and 50% of maximal force. Twenty-five subjects finished the experiment. Heart rate increased a mean of 15.1 beats/min [95% confidence interval (CI): 5.5–24.6] from 20 to 50% handgrip contractions, and 20.7 beats/min (95% CI: 11.9–29.5) from 20 to 50% wheel-turn contractions. Heart rate also increased a mean of 13.3 beats/min (95% CI: 10.4–16.1) from handgrip to wheel-turn contractions at 20% maximal force, and 18.9 beats/min (95% CI: 9.8–28.0) from handgrip to wheel-turn contractions at 50% maximal force. We conclude that the magnitude of the heart rate increase during isometric exercise is related to the intensity of the contraction and the mass of the contracted muscle.

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Forearm endurance training attenuates sympathetic nerve response to isometric handgrip in normal humans

Journal of Applied Physiology ◽

10.1152/jappl.1992.72.3.1039 ◽

1992 ◽

Vol 72 (3) ◽

pp. 1039-1043 ◽

Cited By ~ 43

Author(s):

V. K. Somers ◽

K. C. Leo ◽

R. Shields ◽

M. Clary ◽

A. L. Mark

Keyword(s):

Blood Pressure ◽

Heart Rate ◽

Endurance Training ◽

Sympathetic Nerve ◽

Isometric Exercise ◽

Voluntary Contraction ◽

Isometric Handgrip ◽

Nerve Response ◽

The Right ◽

Muscle Chemoreflex

Recent evidence indicates that muscle ischemia and activation of the muscle chemoreflex are the principal stimuli to sympathetic nerve activity (SNA) during isometric exercise. We postulated that physical training would decrease muscle chemoreflex stimulation during isometric exercise and thereby attenuate the SNA response to exercise. We investigated the effects of 6 wk of unilateral handgrip endurance training on the responses to isometric handgrip (IHG: 33% of maximal voluntary contraction maintained for 2 min). In eight normal subjects the right arm underwent exercise training and the left arm sham training. We measured muscle SNA (peroneal nerve), heart rate, and blood pressure during IHG before vs. after endurance training (right arm) and sham training (left arm). Maximum work to fatigue (an index of training efficacy) was increased by 1,146% in the endurance-trained arm and by only 40% in the sham-trained arm. During isometric exercise of the right arm, SNA increased by 111 +/- 27% (SE) before training and by only 38 +/- 9% after training (P less than 0.05). Endurance training did not significantly affect the heart rate and blood pressure responses to IHG. We also measured the SNA response to 2 min of forearm ischemia after IHG in five subjects. Endurance training also attenuated the SNA response to postexercise forearm ischemia (P = 0.057). Sham training did not significantly affect the SNA responses to IHG or forearm ischemia. We conclude that endurance training decreases muscle chemoreflex stimulation during isometric exercise and thereby attenuates the sympathetic nerve response to IHG.

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0836 Self-Reported Difficulty Initiating Sleep and Early Morning Awakenings are Associated With Nocturnal Diastolic Non-Dipping in Older Men

SLEEP ◽

10.1093/sleep/zsaa056.832 ◽

2020 ◽

Vol 43 (Supplement_1) ◽

pp. A318-A319

Author(s):

X Tan ◽

C Benedict

Keyword(s):

Heart Rate ◽

Brain Research ◽

Older Men ◽

Early Morning ◽

Research Society ◽

Adult Men ◽

Nocturnal Dipping ◽

Falling Asleep ◽

Swedish Medical ◽

Insomnia Complaints

Abstract Introduction Aging increases the risk of insomnia and elevated blood pressure (BP). Here, we examined in older men whether reports of difficulty falling asleep (DIS) and early morning awakenings (EMA) are associated with 24-h BP and heart rate. Methods We utilized variables from 995 men (mean age: 71 years) who participated in the Uppsala Longitudinal Study of Adult Men (ULSAM). BP and heart rate were measured over 24 hours. Results Non-dippers (night-to-day BP ratio > 0.90) had a higher risk of hypertension than dippers (systolic non-dippers vs. systolic dippers, OR [95%CI]: 1.64 [1.21, 2.21], P=0.001; diastolic non-dippers vs. diastolic dippers, 1.50 [1.10, 2.04], P=0.01). Compared to men without DIS, men who reported DIS (10% of the cohort) had a higher risk of diastolic non-dipping (1.85 [1.19, 2.87], P=0.006). Similarly, men who reported EMA (19% of the cohort) had a higher risk of diastolic non-dipping than those without EMA (1.59 [1.12, 2.24], P=0.009). Despite a slightly higher nocturnal diastolic BP among men with EMA vs. those without EMA (+1.4 mmHg, P=0.035), no other differences in BP and heart rate were found between men with and those without insomnia complaints. Conclusion Our findings uncover a link between disruption in nocturnal dipping of diastolic BP and insomnia symptoms related to difficulty initiating sleep and early morning awakening in older men. Support Authors’ work is funded by the Novo Nordisk Foundation (C.B., NNF19OC0056777), Swedish Brain Research Foundation (C.B., FO2019-0028), Swedish Research Council (C.B., 2015-03100), Åke Wiberg Foundation (X.T., M18-0169, M19-0266), Fredrik and Ingrid Thuring Foundation (X.T., 2018-00365), and the Swedish Medical Research Society (X.T., P18-0084).

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