Alarming findings! What happens in your muscles in daily routines?

This article is based on Olli Tikkanen's doctoral dissertation "Physiological loading during normal daily life and exercise assessed with electromyography " and following video:

65% of the time muscles are inactive

During normal daily life thigh muscles were inactive over 65 % of the measurement time and the longest continuous inactivity periods lasted on average for 14 min. Only a fraction of muscle’s maximal capacity is used during normal daily life. Average muscle activity was only 4 % of maximum which is below the muscle activity level required for walking. Several individuals had average daily muscle activity under 2 % of maximum. Total daily activity could then be achieved by less than 1 hour of stair climbing or 1.5 hours of walking. These individuals could have increased their thigh muscle activity 50 % by standing 3.5 hours more during the day.

Only a fraction of muscle’s maximal capacity is used during normal daily life.

Muscle fiber types and their activation in daily life

There are at least three distinct muscle fiber types that are classified for adult skeletal muscles as follows: slow oxidative (or type I), fast-oxidative glycolytic (or IIa), and fast-glycolytic (IIb). The classification is based on the rate of force production of the fiber. For example, type I fibers are able to produce force or power slower than type IIb but have more endurance, and type IIa fibers are between.

Based on the muscle activity measurements in normal daily life, there are probably a lot of people that do not seem to activate their IIb type muscle fibers possibly at all in years. This could cause those motor units to start getting atrophy (i.e. smaller and weaker) and possibly even dying out. This would lead to considerable decreases in muscle strength and individual getting tired in normal daily activities.

...lot of people that do not seem to activate their IIb type muscle fibers possibly at all in years.

So, practical recommendation based on these finding is to activate your leg muscles strongly even for a few seconds on daily basis! This can possibly prevent losing your biggest motor units. This is recommended for all people and especially those who are getting older. Because the rate of losing the biggest motor units gets faster by getting older!

...activate your leg muscles strongly even for a few seconds on daily basis!

Stair ascending can be a maximal effort to thigh muscles of the elderly

Daily life was shown to be physically more demanding for the elderly due to lower maximum strength levels highlighting the importance of maintaining strength levels with aging. Stair climbing was confirmed as a good alternative to enhance leg muscle strength in older people. The muscle activity patterns reported in the research are significant for understanding muscle activity patterns which are typical in adults and can be used as a reference point for recommendations of avoidance of inactivity. This is important since each activity burst of a muscle initiates the metabolic processes that are important for our health.

...highlighting the importance of maintaining strength levels with aging.

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Written by Samad Esmaeilzade and Olli Tikkanen

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