About Physiology

Rowing is a full body exercise, it uses all the major muscles groups of the legs, torso and arms. Elite rowers are recognized to have outstanding aerobic as well as anaerobic capacities. In a 2000 meter race, rowers utilize a unique physiological pattern. At the start of the race rowers begin with a sprint, this places excessive demands on the anaerobic energy source. This is followed by a time period (usually ranging between 4-7 minutes) of high aerobic steady state rowing and then an exhaustive sprint (again anaerobic) at the finish. Rowing is therefore more of a power endurance sport than a strength sport.

However, rowing does require strength, a rower’s training program consists of a combination of endurance, power and strength exercises. This is a specific program so rowers can train their body to tolerate and adapt to the excessive energy demands. This specific training program includes a mixture of workouts of variety of intensities throughout the year. These workouts vary according to the time of year, in the winter months rowers will focus on ‘conditioning’, this is predominantly endurance training (high volumes of training at low intensities) concentrating on rowing technique and will also include strength training. In the spring months, rowers will start to involve high intensity training in preparation for the racing season during summer.

The anaerobic process occurs when there is not enough oxygen in the blood to produce energy aerobically. This process consumes carbohydrate as its primary source of fuel and produces a by-product called lactate. It is lactate which produces the muscle soreness and fatigue associated with excessive exercise. The anaerobic process provides the majority of the energy used by the fast-acting muscle fibers (crucial to strength and power activities).

Training at anaerobic intensities (85 – 100% of maximal aerobic output) can condition the body’s tolerance of lactate, although the benefit may be more psychological than physiological. It can also increase the aerobic threshold. The level of exercise intensity at which lactate begins to accumulate (lactate threshold) can be altered by improving the efficiency of the aerobic process i.e. by training at moderate levels of intensity.

Prolonged exercise at high intensity not only reduces the weight reduction and aerobic training effects, but the rapid onset of fatigue can cause poor technique which may increase the risk of injury.

A form of anaerobic training is resistance/strength based training.

The aerobic process consumes fuel in the presence of oxygen (supplied by the flow of blood) producing by-products, carbon dioxide and water, which are expelled by respiration and perspiration. The aerobic process provides the majority of the energy used by the slow acting muscle fibers (crucial to endurance activities).

At lower intensities the body uses a mixture of fat and carbohydrate as its source of fuel. If the exercise objective is weight loss, it is necessary to burn as much fat (as opposed to carbohydrate) as the source of fuel as possible. This is best achieved at lower intensities and over longer durations. As soon as the intensity is increased the aerobic process starts to burn more carbohydrate and the fat loss effect will be reduced. A low intensity (60 – 70% of the maximal aerobic output) is typically that at which you can hold a conversation: it is by no means strenuous and is about that achieved by a brisk walk.

If the exercise objective is aerobic (cardio-vascular/endurance) training then it is necessary to exercise at an intensity which will avoid fatigue due to lactate build up. This is best achieved at moderate levels of intensity over medium/long durations.

At about 70 – 80% of the maximal aerobic output, lactate begins to accumulate in the blood supply at a greater rate than it can be extracted by the liver, kidneys and other organs. Exercising above this intensity will cause progressive accumulation of lactate in the blood, increased heart and breathing rates, muscle fatigue and, eventually, the cessation of exercise. Prolonged exercise at or below this intensity will maintain lactate at non-fatiguing levels and exercise duration will be limited solely by the depletion of available fuel stores.

A sustained exercise program of aerobic conditioning will improve the efficiency with which the respiratory and cardiovascular system can supply oxygen. This improves lung function, heart function, vascular efficiency and capillary growth, leading to improved well being and endurance.

In this module, we have separated exercise into two distinct groups;

Aerobic Based

Anaerobic Based

When we exercise, the body generates energy (by burning fuels) to perform work. The principal fuels used are the body’s stores of fat, carbohydrate or protein. These fuels can be converted into energy by one of two processes, the aerobic metabolic process or the anaerobic metabolic process.

At the beginning of exercise, energy is initially produced anaerobically until the respiratory and cardiovascular systems respond and supply the oxygen necessary for aerobic energy production, hence the increase in breathing and heart rates. Once oxygen supply is sufficient, most of the energy will be produced aerobically, with the balance supplemented anaerobically. The lactate formed by this residual anaerobic production is easily dissipated by the body’s organs, avoiding any onset of fatigue.

As exercise intensity increases, the ability of the muscles to produce energy aerobically will reach a limit (defined by the capacity of the respiratory and cardiovascular systems to supply additional oxygen). At this point the body cannot supply enough oxygen, and energy production moves to the anaerobic system. This transition point is the maximal aerobic output and is called the aerobic (lactate) threshold. Exercise above this level causes a rapid build-up of lactate, leading to muscle fatigue which will cause cessation of exercise.

Knowledge of the aerobic/anaerobic process is essential for the successful attainment of specific exercise aims. Fat burn (weight maintenance), cardio-vascular training (cardio-vascular or endurance fitness) and anaerobic training (tolerance to fatigue) all rely on an understanding of the way our body produces energy.