The Urban Trainer Blog - UK

There are five internal variables that will have an effect on our body’s ability to perform at optimal levels:

Ventilation

Resistance to airflow in the breathing airways varies throughout the day. It has been shown that the greatest resistance occurs early in the morning between 3am and 8am. As a result it is inadvisable for asthmatic athletes to perform strenuous training early in the morning.

Body temperature

Our body temperature varies by as much as 1ºC over the course of a single day. The peak temperature occurs at around 6pm with the lowest temperature at around 6am. Body temperature has a direct effect on the speed of nerve impulses, with a rise of 1ºC in body temperature increasing nerve impulse speed by 2.4m/sec. This would suggest that we would be more powerful in the evening.

Flexibility

The range of motion about a joint increases directly with body temperature. This would indicate that athletes are less likely to injure themselves in the evening, as body temperature peaks at around 6pm. At this time, stride length in older runners and stroke length in rowers may be longer.

Adrenalin

Blood levels of adrenalin (a stimulator of energy production, heart rate and alertness) peaks in the afternoon. This fact combined with an increased body temperature in the evening, would indicate that late afternoons would be the optimal time to exercise.

Digestion

Stomach emptying rates and daily absorption rates are subject to variations throughout the day. Stomach emptying in the evening is about 50% slower than for the same size meal taken at 8am. This would suggest that it is advisable to have a big breakfast.
Strength, power and endurance One of the biggest influences on speed, power, endurance and strength is our body temperature, which peaks at 6pm. Again this would suggest that the best time to exercise is in the late afternoon/evening. In addition, research has been undertaken on the daily variations in strength, power and endurance.

Strength and power

Over the course of a day, strength variations can differ by about 6%. It appears that strength levels peak in the late afternoon. Using the standing long jump as an indicator of lower body power, it has been shown that the optimal performance levels are achieved at around 6pm. This is the same time as peak power for a bike sprint. The only problem with training this late is tiredness brought on by a hard day’s work.

Endurance

A study of swimmers in the late 1980s showed that the evening was the best time for both sprint (100m) and endurance (400m) swims. Studies have also shown that swimmers produce the most power when body temperature is higher, which is in the evening. Research from Canada has revealed that cyclists do more work on a windtrainer in the late afternoon compared with the morning.

Summary

It would appear that the evening is the best time for strength training and endurance workouts such as anaerobic threshold workouts, interval training or speed work. One of the main reasons cited for this is the fact that are body temperatures are warmer. In the evening, it would appear that we are able to do more work and are less at risk of injuring ourselves.

James Bud,
www.ClubKensington.com