280119 Resistance Training in Cold Weather part 2
Resistance training places high internal and external load demands on the human body. It must be physically prepared to meet and exceed these artificially designed stresses. To successfully adapt, conditions within the body must be favorable. Temperature variations, however, can sometimes overpower the metabolic responses of the organism
The United States Air Force conducts one of the world’s premier Air Crew Survival Schools. The training provided through this school specifically addresses cold weather survival by stating the following in the instructor’s manual
“Cold is a serious stress source, even in mild degrees it lowers efficiency. Extreme cold numbs the body and dulls the will to do anything except get warm”. Cold numbs up the body by lowering the flow of blood to the extremities (we use these in ALL of our exercises) and results in sleepiness”. (USAF, 38)
The authors of Exercise Physiology state: “the normal heat transfer gradient is from the body to the environment, and core temperature is generally maintained without physiologic strain. In extreme cold however excessive heat loss can occur, particularly when the person is resting.” (Katch, 502)
Resting between sets is normal, especially when working in the 85-95% 1RM range. A recent article by Jason Schniepp, et al.,in the Journal of Strength and Conditioning Research, reported the results of test run on ten well-trained cyclists’ and their response to the cold water immersion.
The cyclists, who were exposed to cold water prior to a strength-cycling test, clearly showed the adverse effects the cold temperature had on power output. The cold affected blood flow, metabolism, and the balance of agonist-antagonist muscular activity. “These factors will undoubtedly affect the rate of energy production and muscular efficiency.” (Schniepp, p561)
Furthermore, G.M. Ferritti et al.’s work reported in “Effects of temperature on the maximal instantaneous muscular power of humans”, Euro j. Appl. Physiol. 64:112-116. 1992 and cited by Schniepp “demonstrated a temperature-dependent relationship on the rate of Adenosine Triphosphate hydrolysis, as a reduction in ATP resynthesis occurs with a concomitant decrease in the rate of cross bridge detachment. A relatively greater number of cross-bridge attachments have been found in cooler muscles, resulting in an increase in power absorption proportional to the external work required to lengthen the muscle.” If ATP is slow in breaking down, power decreases cannot be far behind
J.A. Faulker, et al’s report entitled “Muscle temperature of mammals: Cooling impairs most functional properties,” Am. J. Physiol. 28:259-265. 1990, (cited also by Schniepp) suggests, in addition, that:
• “an increase in power absorption by antagonist muscles after muscle cooling may affect coordination, mainly manifesting at faster contraction velocities.”
• “results from this study demonstrated a significant condition by trial interaction as maximum power decreased significantly more after cold water immersion than under normal conditions.”
• “in cooler muscles there is an extended time of relaxation that reflects prolongation of cross-bridge attachment and will result in a reduction of cross-bridge cycling. A reduction in muscle temperature may also impair the activation of motor units during a short time interval, possibly because of lower nerve impulse frequency. As a result, coordinated movement may be affected adversely. The body tries to remain at the optimum temperature through a series of internal regulating mechanisms.”
• “the thermo regulatory defense against cold is mediated by internal temperature NOT by the body’s heat production per se,” according to Katch, et al. “The greatest contribution of muscle to defend against cold occurs during physical activity.” (Katch, 503)
Shivering is the body’s attempt to heat itself up through muscle action but it stops at core temperatures of 85-90 degrees. Normally a person exercising will not become this cold. If so then something is drastically wrong.
References Cited for Resistance Training in Cold Weather:
Arnheim, Daniel D. Modern Principles of Athletic Training. Mirror/Mosby. 1989: 303-4.
Houston, Charles, S., M.D. Merck Manual of Medical Information. Simon and Schuster. 1997:1345-7.
Katch, F.I, V.L. Katch, and W.D. McArdle. Exercise Physiology. Lippincott. 1996 (4th ed.): 351, 502-3, 505-21.
Michele, Lyle, J. The Sports Medicine Bible. Harper Collins.
Schneipp, Jason, Terry S. Campbell, Kasey L. Lincoln Powell, and Danny M. Pincivero. “The Effects of Cold-water Immersion on Power Output and Heart rate on Elite Cyclists.” Journal of Strength and Conditioning Research. 16 (Nov. 2002): 561
Search and Rescue Survival Training. Department of the Air Force, USAF. 1985. (Currently in use at the Survival School)