Leg strength gets a push from training technique

Jul 26 2005

A pair of studies published recently in Medicine & Science in Sports & Exercise (MSSE), the official scientific journal of the American College of Sports Medicine (ACSM), underscore the relevance of sports and exercise research to this year’s Tour de France. One study accurately predicted Lance Armstrong’s time in a stage of the 2004 race, while another points to an effective training technique for aspiring cyclists.

Untrained subjects who were not cyclists showed significant gains in leg strength from a training technique known as maximal strength training, in what is thought to be the first study to measure the effect of strength training on cycling economy in subjects who were also not doing cycle training. The research was published in the July issue of MSSE.

The study measured gains in cycling economy, which is the energy cost of performing a given amount of work on the cycle ergometer. A reduction in the energy cost of doing a given amount of work implies improved cycling economy. “We were surprised that subjects showed a boost in cycling economy for high-intensity cycling, but not low- or moderate-intensity cycling,” said Donald A. Schneider, Ph.D., who headed the Australian research team. “Also, cycling economy improved without a significant change in aerobic capacity or the blood lactate threshold.” The blood lactate threshold indicates the work intensity at which lactic acid concentration in blood rises significantly above the resting level, influencing exercise performance.

Schneider and associates followed seven male subjects in their 20s who were neither training nor participating in exercise more than twice a week. They measured leg strength, maximal oxygen uptake, peak cycling power, and cycling economy before training, after four weeks, and again at the completion of the eight-week experiment.

In contrast to traditional resistance training, maximal strength training consists of fewer than six high-intensity repetitions with the concentric phase of lifting performed as quickly as possible. The training was performed on a hack-squat apparatus (weight-lifting machine used to strengthen the legs and buttocks). Subjects in this study lifted 85 percent of their one-repetition maximum in four sets of five repetitions each for three sessions per week.

“What’s distinctive about this study,” said Schneider, “is that the regimen consisted solely of maximal leg-strength training. Normally, cyclists train for endurance but may not include conventional strength training off the cycle in their training regimen. Other studies have examined the effects of traditional strength training in cyclists who were also participating in endurance training. The design of this experiment allowed us to isolate the effects of maximal strength training in untrained individuals, which we found very revealing.”

Participants showed significant increases in lean-leg muscle mass in the first four weeks of the study, with no significant increase after eight weeks of training. Leg strength increased significantly over the training period.

Schneider cautioned that, while the study revealed benefits of maximal strength training for subjects who also were not doing cycle training, it is possible that highly trained cyclists who also were undergoing cycle training might not see the same effects. More research is needed to determine if maximal strength training improves cycling economy in highly trained athletes who also are undergoing cycle training.

A new mathematical model predicted—within one second—Lance Armstrong’s time in Stage 16 of the 2004 Tour de France. Armstrong won the grueling l’Alpe-d’Huez time trial in 39 minutes, 41 seconds. The model developed by Daniel P. Heil, Ph.D., FACSM, predicted 39:40 (99.958 percent accuracy). Heil’s calculations for the 15.5-km run included grade or slope, aerodynamic drag, gravity, and Armstrong’s power supply and body position. His research was presented last month at ACSM’s Annual Meeting in Nashville, Tennessee.

“A model like this requires many extrapolations,” said Heil. “We must have done something right. Some things must have been off, but it’s a good start at modeling what someone can do in a time trial.”

A cyclist himself, Heil chose to model the l’Alpe-d’Huez stage, which race officials had established as a time trial event for individual riders in 2004. Team events present many more variables, making calculations much more complex. Compared with time trials, “Road cycling has a huge dose of applied physiology and physics intermingling to predict complex behavior,” said Heil. “There’s no way any model can accurately predict it.”

Heil’s model calculated the net power required to overcome gravity, aerodynamic drag, and rolling resistance, compared with Armstrong’s ability to generate power for forward movement. Assumptions included the racer’s body mass, equipment (shoes and helmet) and bike mass, as well as a 500-watt power output. Other factors included race officials’ 16 published combinations of road distance and average grade for the l’Alpe-d’Huez.

The American College of Sports Medicine is the largest sports medicine and exercise science organization in the world. More than 20,000 International, National, and Regional members are dedicated to advancing and integrating scientific research to provide educational and practical applications of exercise science and sports medicine.