COLD WATER IMMERSION IS NOT A NEW CONCEPT BUT ITS BECOME A VERY HOT TOPIC!
Cold therapy (therapeutic hypothermia ) appears to have been used as far back as ancient Greek and Egyptian times for treating some conditions and promoting robust health.
The beneficial effects of cold exposure (in safe conditions) is probably due to hormesis. The saying "what doesn't kill you, makes you stronger", best describes this mechanism.
Hormesis is a favourable biological response to a mild stressor. Hormesis triggers responses that provide protection and help the body adapt to future, more harmful biological stressors. A means of developing resilience.
The first time one gets into an icy body of water or even cold shower, its a nasty shock that can leave us gasping and reaching for the safety of a fluffy warm robe.
THE COLD SHOCK RESPONSE results in a cascade of physiological responses throughout the body. However, with repeated exposure, the human body adapts and and we become habituated to this cold environment as the cold shock response diminishes.
Coldwater immersion (CWI) is a popular post-exercise recovery strategy used by athletes in multiple disciplines during training and competition.
Research shows that CWI in general can beneficially influence recovery from physical performance but there are mixed results, and the timing of cold exposure is an important consideration.
Cold exposure immediately after exercise may reduce the hard-earned benefits of training adaptations by blunting the immune response. Immediately after exercise, blood concentrations of pro-inflammatory cytokines and free radicals (ROS)increase. In response, the body's anti-inflammatory protein peak within the first hour after exercise. Timing CWI for endurance athletes may be the answer. Applying cold 2-4 hours after exercise may mitigate this response.
RECOVERY FROM EXERCISE IS CRUCIAL TO ATHLETES
It does however, depend on what you are trying to achieve with your training.
Are you pushing for ADAPTATION or OPTIMISATION?
If you are training for ADAPTATION TO HYPERTROPHY (muscle growth), DO NOT jump into the ice bath or cold water immediately after your workout.
Use CWI on rest days or endurance exercise days. CWI has been shown to blunt the post-exercise adaptive response you are looking for when it comes to MUSCLE GAIN.
Roberts et al. (2015) and Fuchs et al.(2020)have shown that regular CWI attenuates the magnitude of anabolic signalling and protein synthesis, leading to reduced strength and muscle mass gain following resistance training.
Roberts et al (2015) concluded that "Coldwater immersion attenuated long term gains in muscle mass and strength. It also blunted the activation of key proteins and satellite cells in skeletal muscle up to 2 days after strength exercise"
When it comes to OPTIMISATION such as matches or races that are closely spaced or multiple bouts of technical training, then optimisation of recovery is the paramount concern and CWI is warranted.
POSSIBLE MECHANISMS FOR PROMOTING COLD WATER IMMERSION.
Cold (and heat) is a physiological stressor capable of triggering downstream cascades that may result in improvements in muscle oxidative function.
These improvements are particularly beneficial for endurance performance due to the ability to enhance mitochondrial function.
The PCG-1a gene plays an essential role in energy regulation and is involved in exercise-induced increase in mitochondria, known as mitochondrial biogenesis.
The more mitochondria you have and the more efficient these mitochondria are, the bigger your endurance engine. PCG-1a participates in glucose and fatty acid metabolism, muscle fibre remodelling and thermogenesis (the production of heat).
Individuals naturally gifted with the GG genotype, will automatically have the advantage of greater mitochondrial biogenesis at baseline.
Either way, CWI seems to enhance endurance ability and recovery by activating the PCG- 1a pathway. An additional mechanisms for activating PCG-1a, is the release of norepinephrine.
NOREPINEPHRINE AND THE BRAIN
It is difficult to ignore the importance of norepinephrine release in response to the cold shock response.
Norepinephrine is a hormone and neurotransmitter involved in vigilance, focus, attention and mood. Norepinephrine protects against stress-induced depression, worry and anxiety, and helps us perform better mentally and physically under pressure. Norepinephrine plays an integral response in pain reduction by counteracting the the primary stress hormones, cortisol and adrenaline. It also lowers blood pressure, heart rate and inflammation under stressful conditions.
Norepinephrine is obviously a key player in the mood and cognitive-enhancing effects of cold exposure.
Norepinephrine also decreases brain sensitivity to leptin, which influences obesity by creating new fat cells and thus promoting fat storage. DBH encodes the enzyme, dopamine beta-hydroxylase, which converts dopamine to norepinephrine. Individuals with the TT genotype for DBH, generally have a higher appetite under stress as well as blood sugar irregularities. The T allele may reduce focus and attention as well as increase aggressive outbursts and impulsiveness.
Perhaps the suggestion of 'go take a cold shower to cool off ' has more relevance than we imagine.
Those with the CC genotype show strong emotional footing during challenging and demanding circumstances, good cognitive function under stress and have a reduced risk for stress-induced headaches.
VARIOUS COLD THERAPY MODALITIES
1. COLD WATER IMMERSION (CWI) involves submerging one's entire body in water typically at or below 15*C (59*F). This can be achieved with cold baths or open water. Moving water is colder than still water. If you are in a tub, make sure you move your body or activate the water to remove the thermal layer that is created when motionless.
2. LOCAL CRYOTHERAPY involves placing ice packs on different areas of the body, usually joints or muscles, or hands and feet.
3. CRYOTHERAPY CHAMBERS are usually colder than water because humans lose body heat at a much faster rate in water than in air at the same temperature.
Hypothermia can be life threatening and frost bite or cold shock to the heart are also to be avoided in individuals with underlying conditions. Cold therapy should always be used under supervision and medical advice.