Comparing neck extensor muscle function in asymptomatic Canadian adults and adults with tension-type headache: a cross-sectional study

AIM

To further the understanding of the pathophysiological mechanisms underlying tension-type headache (TTH) by comparing the endurance and strength of neck extensor muscles under acute muscle fatigue in participants with TTH and asymptomatic participants.

METHODS

We conducted a cross-sectional analysis of neck extensor muscle performance. Asymptomatic participants and participants with TTH were recruited via social media platforms and from the Université du Québec à Trois-Rivières community and employees. A total of 44 participants with TTH and 40 asymptomatic participants took part in an isometric neck extensor endurance task performed at 60% of their maximum voluntary contraction. Inclusion criteria for the headache group were to be older than 18 years old and to fulfil the International Headache Society classification's criteria for either frequent episodic or chronic TTH. Clinical (self-efficacy, anxiety, neck disability and kinesiophobia) and physical parameters (neck extensors maximum voluntary contraction, endurance time, muscle fatigue) as well as characteristics of headache episodes (intensity, frequency and associated disability) were collected for all participants. Surface electromyography was used to document upper trapezius, splenius capitis and sternocleidomastoids muscle activity and muscle fatigue.

RESULTS

Both groups displayed similar neck extensor muscle endurance capacity with a mean difference of 6.2 s (p>0.05) in favour of the control group (control=68.1±32.3; TTH=61.9±20.1). Similarly, participants in the headache group showed comparable neck extensor muscle strength (95.9±30.4 N) to the control group (111.3±38.7 N). Among participants with TTH, those scoring as severely incapacitated by headaches were the ones with higher neck-related disability (F[1,44]=10.77; p=0.002), the more frequent headache episodes (F[1,44]=6.70; p=0.01) and higher maximum headache intensity (F[1,44]=10.81; p=0.002).

CONCLUSION

A fatigue task consisting of isometric neck extension cannot efficiently differentiate participants with TTH from asymptomatic participants.

Nutrition and Exercise in Sarcopenia

Sarcopenia is a debilitating condition that involves loss of muscle mass and function, which affects virtually everyone as they age, and can lead to frailty and ultimately disability. In growing recognition of the importance of both muscle strength and muscle mass relative to body size in contributing to functional decline, recent definitions have now incorporated grip strength and a correction for body mass as part of the key criteria that define sarcopenia. With this new definition, a much larger population of older adults are now at risk of sarcopenia. In the present article, we reviewed the literature for studies which tested the effects of diet or exercise interventions on changes in lean mass and/or functional outcomes in individuals with either sarcopenia and/or frailty and identified 19 clinical trials. There were a few key findings. First, dietary interventions involving protein supplementation improved functional and/or strength outcomes in a few trials; however, other dietary approaches were less effective. Exercise interventions and combined diet and exercise interventions produced consistent improvements in lower body muscle strength but had less consistent effects on walking speed and grip strength. Lifestyle interventions not involving calorie restriction generally did not induce significant changes in body composition. There were a limited number of trials in which participants with sarcopenia were specifically targeted, and thus there is an important need for more research to determine the appropriate types of intervention approaches for the high risk population of sarcopenic older adults.

Resting heart rate and the association of physical fitness with carotid artery stiffness

BACKGROUND

Physical fitness is known to influence arterial stiffness. Resting heart rate is reduced by exercise and positively associated with arterial stiffness. This study aimed to investigate the role of resting heart rate in the relationship of physical fitness with arterial stiffness.

METHODS

Subjects were 2,328 young adults from the Childhood Determinants of Adult Health study. Cardiorespiratory fitness was estimated as physical work capacity at a heart rate of 170 bpm. Muscular strength was estimated by hand-grip (both sides), shoulder (pull and push), and leg strength. Arterial stiffness was measured using carotid ultrasound.

RESULTS

Arterial stiffness was negatively associated with cardiorespiratory fitness (men P < 0.001; women P = 0.002), and positively associated with muscular strength in women (P = 0.002) but not in men. Resting heart rate was positively associated with arterial stiffness (P < 0.001 both men and women). Adjustment for resting heart rate reduced the inverse association of arterial stiffness with cardiorespiratory fitness by 93.7% (men) and 67.6% (women) but substantially increased the positive association of arterial stiffness with muscular strength among women and revealed a positive association of arterial stiffness with muscular strength among men. These findings were independent of body size, blood pressure, biochemical markers, socioeconomic status, smoking, and alcohol consumption.

CONCLUSIONS

Our findings attribute a key intermediary role for resting heart rate in the relationship between fitness and arterial stiffness, whereby higher cardiorespiratory fitness may reduce arterial stiffness mainly through resting heart rate, and higher muscular strength might have deleterious effects on arterial stiffness that are partially offset by lower resting heart rate.