CYCLING PERFORMANCE TIPS
Last updated: 1/30/2021
Cycling Challenges in Temperature Extremes
Our cells are powered by temperature dependent chemical reactions. These are temperature dependent with temperature extremes
affecting optimum functioning of all cells - brain, heart, as well as muscle contraction.
Lower the the temperature of a cell and these chemical reactions slow. Heat the cell above
the optimum temperature for these enzyme dependent chemical reactions and the cell's metabolic machinery
starts to fail.
The body's temperature is the end product of the balance between heat production (during ATP production
and muscle cell contraction) and heat dissipation from sweating (evaporation) as
well as the shunting of blood to the skin to facilitate the radiation of heat to the environment.
With normal activity, heat production is relatively stable, and it is the modification of heat loss
that is the major factor in maintaining a stable body temperature of (on the average)
of 98.6 degrees Fahrenheit.
High ambient temperature decreases heat radiation, adding to the heat load you develop
from muscle contraction. Then add humid conditions
which decrease the potential to shed heat with sweating and the problem is magnified. At the
other extreme, cold temperatures, the body is challenged to minimize heat loss which is aggravated
by any wind chill effect as well as the return of colder blood to your core from your extremities
which can lower your overall core temperature below the physiologic optimum.
Numerous studies confirm that riding at temperature extremes impacts performance.
This article documents the negative effects of
both high and low ambient temperatures. To quote "The optimal aerobic endurance performance wearing a
cross-country ski racing suit was found to be -4 and 1C, while performance was reduced under moderate
warm (10 and 20C) and cold (-14 and -9C) ambient conditions." Since it is unlikely the temperature had
an impact on equipment, this reflects a decrease in the power developed by athlete.
This cycling specific study
"demonstrates .... a clear effect of temperature on exercise capacity....following
an inverted U relationship."
The optimal environmental temperature for endurance exercise performance is
within the range of (10 - 17 degrees Centigrade / 50 - 63 degrees Fahrenheit)
Then there are the equipment impacts to consider, especially in colder weather. This
website shows the
impact of low ambient temperature on both air resistance and the rolling resistance of your tires slow times compared to
a similar power output on a summer outing.
In addition to the impact of temperature extremes on the cells energy producing metabolic pathways,
what other factors might lower power output in extreme temperatures?
- For the cold, there is clear evidence
that skin temperature (and presumably extremity muscles as well) are impacted. To quote:
"During the time course mean skin temperature decreased significantly with reduced ambient temperatures ..."
And as your body cools (in this example) it seems likely that there is an effect on the contractile
performance of the muscles directly as well as the blood flow to provide oxygen and nutrients.
The net effect is a significant impact on power out put as demonstrated in
this study - which again noted the association
of a decrease in power output with the decrease in skin temperature.
- Then there is the "internal governor" effect. A central anticipatory
component with a subconscious change in performance to maintain a normal core temperature. This
study is about heat effects (but I
think we can assume a similar process to protect core temperature takes place with excessive cold
temperature). To quote: "This adaptation appears to form part of an anticipatory response which
adjusts muscle recruitment and power output to reduce heat production, thereby ensuring that thermal
homeostasis is maintained during exercise in the heat."
Mitigation of Extreme Heat and Humidity
A number of techniques have been shown to be of benefit. In
competition a number of studies have shown the benefit of precooling so the athlete starts the
event at the lower end of their ideal core temperature.
For those of us doing recreational riding, drinking a cold beverage provides the easiest solution.
delay a rise in core temperature. And it did increase
time to exhaustion performance, but just shy of the level defined as "statistically significant". A
second study supported the benefit of drinking cold beverages and
again demonstrated an increase in performance (this time statistically significant). Bottom line? I add ice to my
water bottle, and if I remember, actually put the bottle, partially filled, in the freezer the night before to
form an internal "ice cube".
Training and competing in the heat.
I recently had a personal encounter with the effects of riding without adequate
acclimatization to the heat. I train in the NW (Seattle) but was riding in the Sierras
in California. On day 2 of a multi-day ride I had my first cramps (ever) while on the
bike. Quad cramps that almost kept me from finishing. It was 95 degrees, we were climbing
Emigrant Pass (8000 feet), my gloves were white with salt, and I'm sure I was not
drinking enough. Fortunately they had electrolyte powder at the next rest stop, and I
took 10 minutes to drink a couple of water bottles or rehydration fluid. And I slowed
down. Lesson learned. As I read this
recently published article, it definitely resonated. I'll quote a few pertinent sentences.
- Only training in the heat will do the trick. "Although regular exercise in temperate
conditions elicits partial heat acclimatization, it cannot replace the benefits induced
by consecutive days of training in the heat."
- It will take 1 to 2 weeks for maximum acclimatization. "Most adaptations (ie, decreases
in heart rate, skin and rectal temperature, increases in sweat rate and work
capacity) develop within the first week of heat acclimatization and more slowly in the
subsequent 2 weeks...(even trained athletes) may require 6-10 days to achieve near complete
cardiovascular and as much as 2 weeks to optimize aerobic performance (ie, cycling time trial)
in hot ambient conditions."
- Hot and humid is more stressful than hot and arid. "Although scientific support for this
practice is still lacking, it may potentially be beneficial for athletes to train in
humid heat at the end of their acclimatization sessions to dry heat to further
stress the cardiovascular and thermoregulatory systems."
- If you are going to a hot climate, it may be time to move the trainer into the sauna.
"Athletes who do not have the possibility to travel to naturally hot ambient conditions
(so-called 'acclimatization') can train in an artificially hot indoor environment
- And finally, hydration is essential. Even though I have, on other pages, quoted a few studies
that suggest hydration is too highly stressed, if you are competing in hot temperatures,
are not hydrated, and are not sweating, the effects of heat are multiplied. And you need to
take salt (electrolytes) as well as plain water.
- Before training and competition in the heat, athletes should drink 6 mL
of fluid per kg of body mass every 2-3 h, in order to start exercise euhydrated.
- Athletes training in the heat have higher daily sodium (ie, salt) requirements
than the general population. Sodium supplementation might also be required during exercise.
- For competitions lasting several days (i.e., cycling stage race, tennis/team sports tournament),
simple monitoring techniques such as daily morning body mass and urine specific gravity
can provide useful insights into the hydration state of the athlete.
- Adequately rehydrating after exercise-heat stress by providing plenty of fluids with
meals is essential. If aggressive and rapid replenishment is needed, then consuming
fluids and electrolytes to offset 100-150% of body mass losses will allow for adequate rehydration.
- Recovery hydration regimens should include sodium, carbohydrates and protein.
Indoor training on rollers or a dedicated bicycle trainer present similar heat challenges.
article summarizes the concern as well as offering reasonable
adaptations when it is the only training choice available.
Mitigation of Extreme Cold
Does riding in cold weather increase the odds of cycling injury?
suggests joint injury as a possibility. What does the literature have to say
Interestingly there is very little science which suggest that aside from frostbite from
skin exposure (especially on the face and feet) and decreased performance in "cooled" muscles
- the opposite of the warm up effect we have all experienced. Falling on an icy spot or from being
distracted by the cold are reasonable possibilites, but are really indirect cold injuries.
For those of you that might be worried about long term harm, such as arthritis, there are no annecdotes or
data. This suggests (to me) that long term physical issues resulting from winter riding are not an issue,
and riding in the cold is no riskier physically than any other time of the year. And if you are in
the group that experiences knee discomfort after riding, a pair of tights or knee warmers is an easy solution.
Proper clothing provides the best option, although there is still the overall impact of the general heat loss
from breathing cold air as well as the breathability of most fabrics. Put on a windproof barrier and the
challenge now becomes prevention of sweating and damp clothing that increases the clamminess with any slowing
of pace and internal heat production.
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