How to stay strong as you age
From around the age of 60, most people will notice a considerable decrease in muscle strength. It’s believed that as you get older, muscle size and function are reduced, inhibiting your ability to produce force. Daily tasks you once took for granted, such as carrying groceries or even climbing a small flight of stairs, become a real chore.
Strength loss with age is not only an inconvenience, it also increases the risk of falls and can rob you of your independence. Many argue that exercise is the key to preventing this: run more, lift more and stretch more. Yet is this really the answer? Sure, lifting weights or walking the dog will make you feel and look better, but how does it all work? What is actually going on inside that will enable you to walk, run, drive or even simply rise from your chair as you age?
In reality, it’s all about the brain. To understand this we must first learn how the brain allows you to move.
Stop or go
Movement is simply a change in your position that may or may not entail a change in your location. The brain initiates movement by stimulating the contraction of muscles.
Your brain governs your muscles by sending messages from a part of the brain known as the reticular activating system to another part of the brain known as the motor cortex (the top part of your brain involved in planning, control and execution of movement).
From the motor cortex, the message travels down the corticospinal tract (the main highway carrying messages down the spinal cord), until they reach an intersection. At this intersection the message is handed over to nerves known as efferent neurons, which carry the message to the muscle fibre. The message tells the muscle to either twitch (contract) or not to twitch. The confusing thing is this message must come several times over in order for a muscle to contract.
The strength of a movement is dependent on several factors. The reticular activating system will send some messages encouraging contraction and others inhibiting contraction. If there are more inhibitory messages than excitatory messages the muscle fibre will not contract. Although it may seem impractical, neural inhibition plays an important role in our muscles’ ability to adjust to certain movements, assist in balance and maintain correct posture.
Movements that require significant strength are impeded by neural inhibition. Too much neural inhibition can result in a lack of strength. Thankfully, the use of a specific resistance training program can reduce excessive neural inhibition.
Firing frequency
Nerve impulses usually arrive at a muscle in a series of closely spaced action potentials. Generally, the more frequent the arrival of these impulses, the stronger the contraction of a muscle. As you age, the frequency at which a muscle fibre receives such messages declines. Muscle contraction becomes longer and slower, reducing your ability to perform daily tasks and increasing your risk of falls.
Research has shown that resistance training (lifting weights) may overrule this decline, allowing the muscle cells of the elderly to fire at a similar pattern to that of the younger individual.
It’s also suggested that resistance training may alter the pattern at which these impulses arrive. The onset of a muscular contraction is often marked by an irregular increase within the consistent pattern of the motor unit train. That is, instead of messages arriving in evenly spaced intervals, there is a sudden flurry or bombardment. This phenomenon is believed to occur to produce a rapid increase in muscular strength and has been shown to increase following exercise training.
The speed of muscle contraction has been shown to decrease by up to 40 per cent with age. Impairment to contractile velocity can have a considerable impact on your ability to move and has even been linked to the incidence of falls in the elderly.
High-intensity resistance training increases muscle fibre diameter and power, improving the speed of muscle contraction. Although its influence on force production isn’t as directly significant, maintaining contractile velocity of muscle is important with age as it allows you to react to and complete tasks quickly.
Learn to be strong
Research has shown that gains from a one-off resistance session can be maintained for up to two weeks despite the fact that no physiological adaptation has occurred and even if you have refrained from similar exercise. It appears that through just one session the somatosensory cortex of the brain has “learnt†how to maximally activate the muscle, indicating that resistance training may not only improve neuromuscular function but also “teach†the brain pattern that is required for increased strength. Of course, long-term resistance training is also required to truly maintain your muscle strength. Here are the types of exercises you should choose:
Tips to stay stronger longer
Functional exercises
Although resistance training can change the way your nerves perform while on the corticospinal tract, practising repetitive and simple weight-bearing tasks won’t alter the functioning of the motor cortex. In other words, although traditional weight training will cause your muscle to contract with more force, the planning, controlling and execution of movements will remain limited.
In light of this, your resistance program should incorporate the use of functional exercises that are more complex in nature and place a greater focus on stability, balance and posture. It could be expected that areas of the brain such as the cerebellum would provide the motor cortex with additional information regarding the positioning of body limbs, posture and changes in equilibrium specific to the movement. This would inevitably alter the way in which the motor cortex functions and improve the efficiency and effectiveness of movement.
Target your exercise
Individuals who train legs together as one unit fatigue less in combined legs exercises, while those who train legs individually fatigue less in tasks requiring the isolation of a single leg. This leads to the obvious conclusion that the commands given by the motor cortex involving bilateral (one-leg) are significantly different from those given for unilateral (two-leg) exercise.
As a result, resistance exercises should be performed with specific consideration for functional tasks of daily life. For example, perform traditional squats for assistance in standing from a chair or one-legged squats for improved stair climbing. Target your exercise at the strength you need.
Train for power
Power exercises will allow you to recruit more muscle, increase contraction speed and improve the rate of motor unit firing. As a result, resistance exercise focusing on power is of more benefit to performing daily tasks than strength alone. There are several ways you can approach a power program, but recent research has suggested that performing movements in a fast motion with a relatively low load is best for improving balance as you age.
Use eccentric contractions
Generally, a muscle either shortens (concentric) or lengthens (eccentric) during contraction. There are several strength-related benefits of eccentric exercises:
Use mental practice
After a weight session, the body requires up to 72 hours of recovery to repair damaged muscle tissue. What if you could somehow continue to train during this period without jeopardising your body’s ability to repair? Wouldn’t this lead to increased strength gains?
Studies show that simply playing a movement over and over in your mind can increase the cortical output signal from the motor cortex, possibly improving muscle activation and strength gains. It may also be useful in retaining skills specific to resistance exercise, particularly during periods of inactivity or immobilisation.
Get motivated
Studies show that when an individual perceives a task to be increasingly harder, more drive is required from the motor cortex in order to avoid fatigue. In other words, it’s possible that the more motivated you are the stronger you can get. A resistance program that uses a variety of goal-orientated tasks (eg perform the task in a certain time) may assist in maintaining motivation. Additionally, listening to stimulating music, rewarding yourself or even training with an encouraging friend may help.
