June 16, 2010
VO2 max is one of the most commonly measured physiological variables. Endurance athletes spend countless hours discussing, comparing and worrying about their VO2 max scores. Cyclists are always quoting VO2 max scores for one top rider or another. Is all the attention that this physiological variable gets really worth all the effort?
VO2 max is the maximum amount of oxygen that your body can take in and use. It is a function of both the body’s ability to deliver oxygen via the heart, lung and blood and the body’s ability to use oxygen in the working muscles and other tissues. While there are some exceptions, Elite cyclists typically have VO2 max scores in the 70-75 ml/kg/min range, similar to that seen in well trained amateur cyclists and some very fit age group riders. In an aerobic sport oxygen consumption is tightly tied to energy expenditure and generally producing more energy means more power and work. The relationship between power and oxygen consumption is not perfect; efficiency or economy play an important role in determining how strong the relationship is in each person.
Gross efficiency, the ratio of power output to power input, is a key determinant of cycling performance (1). A higher efficiency allows a cyclist to work at lower percentages of the VO2 max to accomplish the same or more work as a less efficient cyclist. In fact, a high efficiency rating can make up for lower VO2 max scores. Alejandro Lucia and coworkers (2) from the Universidad Europea de Madrid examined the relationship between VO2 max and cycling efficiency and gross efficiency in a group of elite cyclists. The subjects in this study were all world class riders having won at least one major professional race, defined as stage in the Tour de France, Giro d’Italia or the Vuelta a Espana, or finished in the top three at the World Championships. Hemoglobin and hematocrit levels were measured prior to the start of the study to ensure they were within normal physiological ranges. All subjects performed a VO2 max test following standard protocols. Later the same day they performed a 20 minute constant load test where they road at 80% of their VO2 max. VO2 max values in the subjects varied from a high of 82.5 ml/kg/min to a low of 65.5 ml/kg/min. Cycling efficiency varied from 97.9 watts/L O2/min to 72.1 watts/L O2/min. There was a significant inverse correlation between VO2 max and cycling efficiency. This means that those with the higher VO2 max scores had the lowest efficiencies and those with lower VO2 max scores had higher efficiency. A similar pattern was seen in gross efficiency. Power to weight ratio at VO2 max was not significantly different between riders, they were all in the 4.9-5.4 W/kg range. Interestingly two of the most accomplished riders, a road race and time trial world champion and climbing specialist who had won five stages in the Tour de France both had VO2 max score under 70 ml/kg/min.
This study clearly shows that VO2 max is less important than efficiency in cycling performance and that a high level of efficiency can make up for a lower VO2 max. This pattern is not unique to cycling it has also been seen in running (3) and rowing. In an upcoming article we will look at the various factors that contribute to efficiency and how to improve your cycling efficiency.
So the next time someone start bragging about their VO2 max score ask them about their efficiency rating. Their high VO2 max may just mean that they are very inefficient riders.
- Coyle, E. (1995). Integration of the physiological factors determining endurance performance ability. Exerc Sport Sci rev. 23: 25-64.
- Lucia, A. et al. (2002). Inverse relationship between VO2 max and economy/efficiency in world class cyclists. Med Sci Sports Exerc. 34: 2079-2084.
- Saltin et al. (1995). Morphology, enzyme activities, and buffer capacity of Kenyan and Scandinavian runners. Scand J. Med Sci Sports. 5: 222-230.
June 10, 2010
Modern strength training programs for athletes spend an inordinate amount of time focusing on using unstable surfaces, single leg exercises and balance training to improve speed, strength and power. There is currently no research that shows that these types of training improves athletic performance (1) but it has been well established that training on unstable training results in significantly less force development and loads that will limit strength gains (2). All this balance and stability training has come at the cost of building strength in traditional exercises like the squat, bench press, deadlift, and power clean yet these exercise have time and again been shown to be key to athletic performance. A recent study at Applalachian State University examined the relationship between squat strength and sprint speed(3). The subjects were a group of 17 football players with an average height of 1.78m and an average weight of 85.9 kg. 1RM squat was assessed on the first day of the study. All subjects were required to squat to a 70o knee angle, making it a deeper squat than the 90o knee angle that many people use in training. A deeper squat will normally decrease the amount of weight lifted. The average 1RM squat was 166.5 kg. Later in the week the subjects performed electronically timed 5, 10, and 40m sprints on a standard outdoor track surface. When they analyzed the data they found significant correlations between squat strength to body weight ratio and the 10m and 40m sprints. When the group was divided into those with a squat to bodyweight ratio of greater than 2.1 and those with a ratio of less than 1.9 those with the higher strength to weight ratio were significantly faster than those with a squat to bodyweight ratio less than 1.9. This study adds to the growing body of evidence that shows the importance of traditional strength training exercises for improving athletic performance.
So why does improved strength improve speed and acceleration? Think back to your high school physics class and you might remember the formula F=ma; force is equal to mass times acceleration. Transforming the formula to solve for acceleration we get a=F/m; acceleration is equal to force divided by mass. When we are speaking of running or jumping activities the mass is your body weight. If you increase your strength to body weight ratio you will increase your speed and acceleration; it is simple physics.
Unstable surface, single leg and balance training may be fine during a warm up but they are no replacement for good old fashioned deep squats when it comes to increasing strength and improving speed and power that translates to athletic ability. So if you want to get faster stop using circus tricks and lift some real weights.
- Wilardson, J. (2004). The effectiveness of resistance exercise performed on unstable equipment. JSCR. 26(5) 70-74.
- Behm et al (2002). Muscle force and activation under stable and unstable conditions. JSCR 16(3) 416-422
- McBride et al (2009). Relationship between maximal squat strength and five, ten, and forty yard sprint times. JSCR. 23(6) 1633-1636.
June 8, 2010
Heat is a major limiting factor in endurance performances. It has been quite well established that as temperature increases so does marathon time. Over the past 5-10 years more and more attention has been paid to dealing with heat stress while training and competing. Ice vests have proven to be quite effective when worn for a period of time immediately prior to a race but are often impractical and quite expensive. There is evidence that consuming cold water can improve time to exhaustion and running performance compared to warm water (1). Recently this idea was taken a step further by a group of Australian researchers. Using a group of ten moderately trained recreational runners, they examined the effects of drinking a Slushie right before running compared to cold water. All subjects participated randomly in both trials, running as long as possible at their aerobic threshold in a warm environment of 34oC and 55% humidity. Before each run the subjects ingested 7.5g/kg of either a Slushie or the cold water. The temperature of the Slushie was -1oC and the cold water was 4oC. Both drinks contained a 5% carbohydrate solution. When the subjects consumed the Slushie they ran 19% longer than after consuming water. Both groups were equally hydrated at the start of their runs but the Slushie group had a lower rectal temperature. Interstingly the Slushie group maintained a lower body temperature for the first 30 minutes of their run but ended up with a higher temperature at exhaustion. The authors have suggested that the colder temperature of the Slushie may have decreased brain temperature and delayed the point where a critically high brain temperature causes fatigue, around 42oC. This study clearly shows that Slushies are performance enhancers when you are exercising in the heat. So next time you head off for a training session run by 7-11 or Mac’s Milk for a quick slushie, it will make those training sessions in the heat more tolerable and even improve your performance.
Lee JK, Shirreffs SM, Maughan RJ. Cold drink ingestion improves exercise endurance capacity in the heat. Med Sci Sports Exerc. 2008;40(9):1637–44
SIEGEL, R., J. MATE´ , M. B. BREARLEY, G. WATSON, K. NOSAKA, and P. B. LAURSEN. Ice Slurry Ingestion Increases Core Temperature Capacity and Running Time in the Heat. Med. Sci. Sports Exerc., Vol. 42, No. 4, pp. 717–725, 2010.
March 18, 2009
Cycling, particularly road racing, crits, and time trials are endurance sports where the training focus is long distance training. Despite the endurance requirements many races come down to a final sprint that is dependant on very short term peak power. Strength training and cycling specific sprint training can improve this ability but the fastest way to bump up your short term power may be a nutritional supplement called Beta Alanine.
Beta alanine is an amino acid the is converted to carnosine in the body. Carnosine is an intramuscular buffer which accounts for about 10% of a muscle’s buffering capacity. During intense exercise there is a build up of H+ from lactic acid and other sources which can negatively affect muscle contraction and contribute to fatigue. Increasing carnosine concentration in the muscle can delay fatigue caused by H+.
A recent study published in the American College of Sports Medicine Journal (Med Sci Sports. Vol 41 pp 898-903) examined the effects of beta alanine supplementation on sprint ability at the end of a 110 min cycling performance. The subjects were 21 male recreationally competitive cyclists divided into a placebo and Beta Alanine group in a double blind fashion so that neither the researchers or the participants knew who was in which group. The Beta Alanine group used 2g per day for the first 2 weeks, 3g per day for the next two weeks and 4g per day from week 5 to the end of the eight- week study. Both groups kept to their normal training routines throughout the study.
Before and after the supplementation was started all subjects completed a simulated 110min time trial immediately followed by a 30s all out sprint. Following the treatment the Beta Alanine group improved their average power over the 30s by 5%; there was no change for the placebo group. Peak power, during the sprint, improved by 11.4% for the beta Alanine group with no change for the placebo group. Interestingly, all of the subjects in the Beta Alanine group saw improvement in both Peak and mean power while many of the placebo group decreased both peak and mean power during the sprint.
Beta alanine has been around for a few years and the research clearly supports it’s use for improving short- term sprint performance in both endurance and speed and power sports. There have been no reported side effects of Beat alanine supplementation.