Modern Athlete Magazine Issue 131, June 2020 June 2020

COACHING BODY SCIENCE Getting Older & Slower Recently I spoke to a master’s runner who, over the last few years, had noticed a small but steady decline in his running pace, with his strides devolving into shuffles. Despite experiencing no pain and having decades of running experience, his strides shortened and his running speed slowed down. So how does a runner’s body change as they age? – BY ERNEST HOBBES, BIOMECHANIST As a runner ages, their lung capacity decreases due to a weakening of the diaphragm and reduction of the size and number of alveoli in the lungs. Maximal heart rate slows down by roughly one beat per minute each year, which means that at 60 years of age, your maximal heart rate is around 40 beats per minute slower than it was when you were 20. Since exercise intensity is related to cardiac output (heart rate x volume the heart can pump per stroke), a reduced maximal heart rate will reduce cardiac output, thus lowering maximal and near maximal exercise rate. As a result, running at the same pace will require a higher percentage of maximal effort, while running at the same relative effort will occur at a slower pace. Flexibility also decreases with advancing age, particularly in connective tissues, such as tendons, as they become less pliable. The muscles also become increasingly inflexible, resulting in a reduced range of motion. This affects the backwards swing of the leg, resulting in an earlier recovery and a shorter cycle, reducing stride length. In a way, this works in tandem with the reduced exercise capacity, as the most economical running intensity is brought a gear down. and forms of exercise the runners participate in, but it is estimated that runners slow down between 0.2% to 1.4% per year. As age advances, the rate of decline increases. Aging results in a decrease in muscle size, particularly in the lower body. In addition, the neural stimulus for muscles to contract activates fewer muscle fibres, resulting in a decrease in muscle strength. Fast twitch fibres, which better accommodate high intensity work, are affected more than slow twitch fibres, which are suited for endurance events. Even though endurance runners rely far more on the slow twitch fibres, fast twitch fibres are also used. As men have greater muscular strength, they also have the most to lose, meaning that women can slowly close the gap on their male counterparts as they age. Generally, sedentary adults lose fitness and strength much faster than active adults after the age of 30. The exact rate of decline is dependent on age, activity level There is some good news, though. As a previous article of mine explained, running economy continues to improve beyond the age of 30 due to a constant improvement in running technique. Studies have found that running economy at 40, 50, and 60 years of age show no observable decline. There are a few things runners could do to slow the rate of decline, and my next article will focus on this as well as the risks of activity at an older age. About the Author Ernest is a biomechanical, video, and running gait analyst at the High Performance Centre (HPC) of the University of Pretoria. Images: Pexels When we exercise, we place certain stresses on our bodies which may lead to the loss of micronutrients in the body. These micronutrients play an important role in energy production, maintenance of bone health and adequate immune function, to mention but a few. They also help with the synthesis and repair of muscle tissue during recovery from exercise and injury. Therefore, a greater intake of micronutrients may be needed in athletes for building, repair and maintenance of lean body mass. The most important vitamins and minerals include: • Calcium: Especially important for growth, maintenance and repair of bone tissue, maintenance of blood calcium levels, regulation of muscle contraction, nerve conduction, and normal blood clotting. • Vitamin D: Important for calcium absorption, regulation of serum calcium and phosphorous levels, and promotion of bone health. • B Vitamins: Important to ensure adequate energy production and building and repair of muscle tissue. • Iron: Required for the formation of oxygen-carrying proteins, haemoglobin and myoglobin, and for enzymes involved in energy production. • Zinc: Plays a role in growth, building muscle tissue, energy production and immune status. • Antioxidants – Vitamin C and E, Beta-Carotene and Selenium: Play important roles in protecting the cell membranes from oxidative stress damage. • Magnesium: Plays a variety of roles in cellular metabolism and regulates membrane stability and neuromuscular, cardiovascular, immune and hormonal functions. SO WHO NEEDS TO SUPPLEMENT? Athletes consuming a healthy balanced diet don’t necessarily need to supplement with vitamins and minerals, as their diets will still be adequate to supply these higher micronutrient needs. However, athletes who are at greater risk include those who restrict energy intake or have severe weight-loss practices, those who eliminate specific food groups from their diets, and those who consume unbalanced and low micronutrient diets. Therefore, supplementing with vitamins and minerals will not improve athletic performance in athletes who eat nutritionally balanced diets, and these athletes do not necessarily need to take a multivitamin to meet higher micronutrient demands placed on the body by athletic activities. And you should also always read patient information leaflets before taking supplements, or consult your doctor or chemist when taking other medication. About the Author Christene is a registered dietician based in the Johannesburg area. 33

Modern Athlete Magazine Issue 131, June 2020 June 2020 | Page 33