Growing warmer

Flex, July, 2009 by Jim Stoppani

FACT Warming up is critical for getting your body temperature higher, which helps to keep your tendons and joints pliable and thus prevent injuries.

HYPOTHESIS A proper warm-up is important for muscle growth as well as for strength.

RESEARCH Two studies in particular show just how critical warming up can be. The first is from Arkansas State University (Jonesboro). Researchers compared the one-rep-max strength of subjects on leg extensions and leg curls in a cold environment to their 1-RM strength on leg extensions and leg curls in a warmer environment. The second study, from King's College (London, England), had competitive swimmers and rowers perform 40 minutes of intense exercise either in a room set at about 70[degrees]F or about 40[degrees]F.

FINDINGS The Arkansas State researchers reported that when the subjects performed the 1-RM tests without a warm-up in a room set at 40[degrees]F or 50[degrees]F, they were 10% weaker than when they performed the strength tests in a warmer room set at 60[degrees]F or 70[degrees]F. The UK researchers reported that when subjects exercised at 40[degrees]F their growth hormone levels were less than half of what they were when they exercised at 70[degrees]F.

CONCLUSION Having your body temperature up while you're working out can more than double your GH levels, leading to more strength and muscle size.

APPLICATION Be sure to warm up thoroughly. Of course, this is especially important during the colder months. The colder it is outside and the longer you're outside before getting into the gym, the longer you need to warm up. Go with at least five minutes of moderate cardio or calisthenics on cool or warm days and at least 10 minutes of this activity when it's freezing or below freezing outside. Static stretching is not a warm-up and should be done after workouts.

--Jim Stoppani, PhD

References: M.J. Comeau et al., "Effects of environmental cooling on force production in the quadriceps and hamstrings," Journal of Strength and Conditioning Research, 17(2)279-84, 2003; A. Wheldon et al., "Exercising in the cold inhibits growth hormone secretion by reducing the rise in core body temperature," Growth Hormone and IGF Research, 16(2):125-31, 2006