Doing a warm up before racing and training efforts have become universally accepted as a method of preventing injuries and improving racing and training performances. To question the necessity of performing a warm up before competition or training would have been considered heresy 20 or 30 years ago.
However, a solid mountain of research has been steadily piling up over the years to indicate that warming up the wrong way or under certain circumstances may actually be counterproductive and cause you to run or cycle slower. Surprisingly, there’s also evidence that warming up may not reduce your chances of preventing injuries.
Let’s look at the supposed benefits of doing a warm-up, the different types of warm-up, what the coaches have to say about its benefits, and finally we’ll look at the interesting conclusions that exercise scientists have found.
Preventing Injuries: Purported Benefits of Warming Up
General benefits: Transitions our body from resting state to readiness for a race.
Blood flow: Increases blood flow to the active (working) muscle sites, or lower extremity in the case of running. Blood floods (vasodilation) to our leg muscles and decreases (vasoconstriction) to the non active sites such as the gut and digestive tract.
Oxygen distribution: Distributes higher levels of oxygen to the working tissues, and enhances oxygen dissociation from hemoglobin.
Oxygen uptake: Dilates the alveoli in our lungs, thus increasing our uptake of oxygen well above resting values.
Heart rate: Increases our heart rate from a resting state and moves it closer to our submaximal exercise rate.
Conduction of nerve impulses: The speed at which nervous impulses are conducted along our nerve axons in our central and peripheral nervous systems is also increased, thus making our movements faster and more efficient.
Muscle contractions: Increases the contractile speed and force of our muscle contractions, giving us a more powerful leg action.
Muscle tissue: Active muscles, tendons, and connective tissues are believed to become more elastic, thereby reducing our chances of injury and muscle soreness.
Fuel utilisation: Makes our metabolism more efficient. Exercise scientists surmise that for every one degree increase in body temperature from 98.6 degrees to 101 degrees, we experience a 13% increase in metabolic efficiency, for about a 33% increase in the speed at which free fatty acids are released into the muscle cells—giving us more energy.
Aerobic enzyme activity: At higher body temperatures aerobic enzyme activity appears to be boosted, facilitating the aerobic process via the Krebs cycle.
Lactate threshold: Causes a favorable shift in lactate threshold, meaning that the triathlete will have lower lactate production during the performance.
Second wind phenomenon: Brings together that “meshing” of our neuromuscular, skeletal, cardiovascular and respiratory systems where, after 10-12 minutes of light jogging, our running suddenly becomes smoother and more effortless.
Psychological benefits: Helps stabilize the adrenalin rush before competition, thus helping us control our pre-event nervousness.
Preventing Injuries: Two Different Types of Warm Up
An active warm up involves swimming, running or cycling with the goal of activating the responses listed in the table above.
The less-used passive warm up utilizes heating the body or parts (such as your legs) with external heating agents like hot tubs, hot water bottles, hot showers, or even dressing very warmly.
Active warm-ups are generally recommended for triathletes, unless in extreme cold.
Preventing Injuries: What the Experts say about Warming Up
Gordon Bloch, in his book How to Train for and Run Your Best Marathon, states, “The warmup is the period of easy activity in which you engage in the beginning of the workout in order to get the body physically and psychologically adjusted to exercise. It raises the heart rate and loosens the muscles and connective tissue so that the hard portion of the workout is not a shock to the system. Without a warmup, the body must perform when it is stiff and cold, and this is when injury is more likely to result”.
David Costill, Ph.D., writes in Inside Running: Basics of Sports Physiology, that, “Although the scientific documentation on the value of warm-up is unclear, a slow entry into the intense portion of the workout will lessen the risk of injury and permit some physiological adjustment to the energy demands of the exercise”.
The experts and coaches are generally in favor of athletes performing the warm-up. Interestingly, none of the experts mention that overdoing a warm-up can be counterproductive and actually decrease performance. Warming up for too long in a high heat and humidity environment, for example, would clearly negatively impact performance due to premature dehydration, reduced glycogen stores, and general overheating. Not to mention the redundancy of doing a lengthy warm-up for an extended event like the Ironman triathlon.
Results of the hundreds of research papers done on this topic are mixed. Some show that performance without warm up is no different from performance with prior warm up. Other studies show warming up before a heavy workout or competition is beneficial. A review of the literature done by B. Franks in 1972 found that 53% of the studies to that date supported the proposition that warm-up was better than no warm-up, 7% found that the warm-up was counterproductive, and 40% found that doing a warm-up made no difference to performance.
Studies that look at physiological variables when assessing the effect of the warm-up also find significant enhancements. Martin et al reported an 11% higher heart rate and 8% higher oxygen consumption (VO2) during a 90 second run at 23.6 kph up a 2% grade, compared with runs without a warm-up. These results translate into improved performances. Another study found that 2 different warm-up protocols increased maximum knee extension torque and muscle activation rate, meaning increased strength and speed of the muscles that were tested. Research has also shown that warming-up improves one mile and 2 mile times.
Researchers Inger and Stromme put 6 runners through a 4-minute maximal treadmill run after active, passive, and no warm-up. The warm-up caused higher oxygen uptake, and lower blood lactate concentrations Vs no warm-up—effects that surely would result in improved performance. Another study also found lower lactate levels due to a warm-up.
But as with most research, for every study showing that a treatment is effective, it’s possible to find a study showing that it doesn’t work. A well-conducted study of 9 runners who ran at 105% of maximal oxygen uptake to exhaustion after different types of warm-up showed no improvement in total running time. Contrasting with other study results, no increase in blood lactate oxygen consumption or running economy was found.
Researchers Falls and Weibers failed to find any increase in oxygen uptake during submaximal exercise following an active warm-up. Likewise a study by Gutin, Horvath and Rochelle found no significant differences in performances of 10 minutes of treadmill running at 75% of VO2 max after a 20-minute low intensity warm-up.
A creative study that actually pre-cooled cyclists with cold water before a 30-minute cycling trial for distance found performance was improved from 14.9 km to 15.8 km. in hot and humid conditions. This flies in the face of all we believe to be true about the beneficial effects of warm-up. Imagine a triathlete turning up at a race with some type of portable cooling machine or vest!
What does research show about the belief that the warm-up reduces or has a positive impact on preventing injuries? A plethora of conflicting research also exists in this arena. Some studies show that warm-up is associated with preventing injuries, while others show the opposite.
Walter et al evaluated 1680 runners in the Ontario cohort study and found that runners who never warm up have less risk of injury than those who do. Van Mechelen randomly studied 316 running subjects in a 16-week experiment. The subjects were split up into an intervention group (159 subjects) and a control group (167 subjects). The results were surprising. The control group had 4.9 running injuries per 1000 hours of running while the intervention group (warm-up, cool-down and stretching) had more (5.5) running injuries per 1000 hours of running.
A lab study by Strickler investigated the effect of passive warm-up on musculo-tendinous units of rabbit hind-limbs by heating them to 35 degrees C and 39 degrees C, then subjecting the hind-limbs to a controlled strain injury. The energy measured at strain point was lower at the higher temperature, meaning that warmed limbs were more extensible before reaching breaking point, thus potentially reducing susceptibility to strain and injury.
Researcher Safran summarizes these contradictory results; “Warm-up and stretching are essential to preventing injuries to the muscle by increasing the elasticity of muscles and smoothing muscular contractions. Improper or excessive stretching and warming up can, however, predispose to muscle injury”.
Preventing Injuries: Conclusions
Well, where does all this leave us for preventing injuries? To warm up or not to warm up?
A compilation of the research to date indicates that different types of warm-up are needed for different events, something that coaches are well advised to consider. A one-size fits all warm-up does not appear to be effective for all triathletes.
For intermediate events lasting up to 5 minutes (such as the mile race), warm-up has been shown to improve performance, but not if the intensity is too low (<40% of VO2 max) or if the recovery time before the start is too long (5-10 minutes). The goal of warming up for middle distance events would be to get to the start line with an elevated VO2, while sufficiently recovered from the warm-up.
For distance events over 5 minutes in length (and that’s most of you reading this article), starting with an elevated VO2 max improves performance, but caution needs to be taken not to deplete muscle glycogen or increase thermal stress, or performance will suffer.
Preventing Injuries: Warm up Guidelines
So if you do a warm-up for the short course triathlon, here are some guidelines to follow. The warm-up for anything longer (Half-Ironman and Ironman) needs to be minimal to avoid dehydration, muscle glycogen depletion, and overheating. Warming up should include these activities:
5 to 10 minutes jogging - to increase body temperature
5 to 10 minutes (http://www.brianmac.co.uk/dynamic.htm dynamic stretching exercises – to reduce muscle stiffness)
5 to 10 minutes general and event specific drills – e.g. swimming and/or cycling, while focusing on correct technique (staying relaxed and turning your legs over quickly and efficiently).
Dynamic (ballistic) stretches are more appropriate to the warm up as they help reduce muscle stiffness. Static stretching exercises do not simulate rapid running movement and may actually cause a reduction in leg power, according to some studies.