Cycling in the winter provides a unique challenge for the body. The reduction in air temperature results in increased metabolic rate to maintain body temperature, especially when exercising. This increase in thermogenesis (via hormonal responses and shivering) results in an increase in oxygen consumption. At rest, we generally consume around 3.5 mL^-1.kg^-1.min^-1 of oxygen, however if you are cold enough to shiver, your metabolic rate has increased oxygen consumption up to ~14 mL^-1.kg^-1.min^-1 to increase heat production. 

How Does the Cold Affect Your Performance? 

When unprepared for the cold, skin and core temperature receptors stimulate a response called peripheral vasoconstriction in cutaneous and skeletal muscle circulation. Vasoconstriction is the narrowing of blood vessels which decreases blood flow and therefore heat transfer from the core to periphery. Therefore the cold essentially drives blood away from the exercising muscles, decreasing the delivery of oxygenated blood to the muscles and decreasing the removal of the waste products of exercise and consequently inhibiting performance. However, vasoconstriction does not occur in cerebral circulation and a large proportion of heat loss occurs through the head and can amount to up to 25% of total body heat loss. 

Muscle temperature decreases in the cold reducing maximal strength, power and endurance. The superficial nerves cool and it takes more time to develop force and reduced nerve conduction results in recruitment of fewer muscle fibres, especially those closest to the muscle surface. Chemical reactions slow down and ATP utilization decreases at low muscle temperatures.  

When core temperature is lowered, VO2_max decreases (this is directly proportional to the decrease in core temperature) from a reduction in maximal heart rate and oxygen off-loading at the muscle tissue level. During sub-maximal exercise metabolic rate is increased and the metabolic cost to maintain a pace becomes greater, combined with a reduced VO2_max! Working at a higher rate results in an earlier onset of fatigue, as there is an increased reliance on anaerobic energy production.  

Training and Racing Recommendations: 

Ø       Subcuntaneous fat – the more the better! Yes you can put on those extra few kilos to keep warm in winter. 

Ø       Cold acclimatization – you if are due to race in cold conditions that you are not used to acclimatization at least 10 days before a competition is useful. This can be done training at the coldest part of the day, or in an air-conditioned room (use your imagination!). 

Ø       With 25% of total body heat loss coming from the head, wear something under your helmet, especially if you go for the number one at the barbershop. 

Ø       Go to the toilet just prior to a race/ride. Cold temperatures increase urine formation by decreasing tubular re-absorption of water in the kidneys. 

Ø       Ignore the tough bastard – if you are cold, rug up. You will only decrease your own performance if you resist putting those arm or knee warmers. You will perform better in these if the temperature drops below 15°C.   

Ø       Insulate skin if you want to race in shorts. This can be done using Vaseline or other rubs such as Hot Stuff or Percutane. If you are prone to patello-tendonitis, it is particularly important to keep your knees warm in winter. 

Ø       Don’t wear cotton under tops (ie. Finally throw away your souvenir nationals T-shirt from 1989) as cotton retains moisture against the skin and cools it. Instead go for polypropylene’s that remove moisture from the skin and wearing several thin layers of clothing is better than one bulky layer. 

Ø       Cold air is denser than warm air therefore aerodynamics are reduced = slower speeds. The general rule for performance comparisons is a 10°C drop in temperature equals a one minute increase in time trial time per hour. 

Ø       If you are prone to exercise-induced asthma, you will need a longer warm up in winter to gradually allow your respiratory tract to adapt to warming the inhaled air and attempt to prevent any problems once the race has started. Cold dry air irritates the airways. 

Ø       If riding long hills in training remove your wind vest to allow heat loss and put it back on before descending. It is worth taking the time to take it off so you don’t sweat too much and rugging up before the chilly descent. 

Ø       The good old newspaper trick – putting this underneath your racing jersey is great when racing. When you warm up you can easily get rid of it. 

Ø       Eat more regularly in racing and training, as you will be using more energy. 

Ø       Before a race warm up on a stationary trainer. This will allow the body to warm without having to counter the wind chill factor. Warm up on the trainer, then on the road before the race. 

Ø       Spin more - spinning increases blood flow and therefore helps increase muscle temperature.  

Ø       In case of emergency always have a few dollars in the back pocket, for that urgent hot chocolate J

References: 

Bloomfield, J., Fitch, K.D.  (1992).  Textbook of Science and Medicine in Sport.  Blackwell Scientific Publications. 

Roberts, and Roberts 

Hammes, E.M., & Wells, C.L.  (1986).  Environment and Human Performance.  Human Kinetics, Champaign Illinois. 

Nadel, E.R.  (1992).  Heat Exchange in Hot and Cold Environments.  In: Shephard, R.J., & Astrand, P.O.  Endurance in Sport.  Blackwell Publications, Oxford.