In the last 10 years, modalities for recovery have been created and sophisticated enough to be considered ‘state-of-the-art,’ to aid in accelerating processes crucial to performance enhancement. Processes such as a metabolic response during exercise, in particular, are incredibly complex, yet impressive. It is fascinating that the human body constantly receives stress signals during exercise and decides the most efficient way to generate energy. I worked with swimmers for much of my early career and enjoyed applying science toward understanding the different energy demands of each athlete, based on their race. Swimming has athletes that train and utilize polar opposite energy stores: sprinters and distance. Sprinters spent more time in the cool down pool than distance swimmers, but why? There is specific rationale for giving more time for the sprinters to 'cool-down.' Short-duration, high-intensity activities such as sprinting require a different energy metabolism than slow-paced activity, like the longer distance races. Athletic effort that reaches the level of intensity like the 50 meter freestyle produce metabolic responses that require more recovery and cool down to bounce back before the next event. This same principle can be applied to CrossFit athletes due to the similar demands they face. Below are three qualities of CrossFit that explain why CrossFit athletes may need more recovery than other recreational athletes.
1. The energy metabolism used for CrossFit
Activities in CrossFit are very intense. Intensity is an ambiguous word but in this instance, high intensity can be defined as short bursts of activity that are at an individual's VO2max. The VO2max levels vary person-to-person; it refers to the maximum rate of oxygen consumption during exercise, or more aptly, maximum aerobic potential. During very intense, submaximal exercise, our body cannot provide a sufficient amount of oxygen to continue at this rate; however, providing energy without oxygen is not an issue for the human body. Once there is insufficient amount of oxygen, the body will switch from aerobic metabolism (with oxygen) to anaerobic metabolism (without oxygen). Aerobic metabolism is indefinite while anaerobic can provide energy for shorter bursts of activity that last as briefly as 10 seconds or as long as 2 minutes. Anaerobic glycolysis is also the dominant producer of energy in repeated efforts with little rest. Repeated efforts such as fifty calorie burns on the assault bike followed by a dozen deadlifts have insufficient recovery time to allow replenishment and energy is produced anaerobically. The body never uses just one energy source; rather, it toggles back and forth depending on activity. Before we move on to why this pertains to recovery, a diagram of this energy switch is helpful.
Since this is an article about CrossFit and not ultramarathon running, focus your attention on the pathway that is used ‘without oxygen’ which is the most commonly tapped during CrossFit. Here also, we must debunk the myths about lactic acid. When insufficient oxygen is available, muscles can still break down carbohydrates (glycogen) anaerobically for energy. Pyruvate is converted to lactic acid, and then to lactate and hydrogen ions. As you can see, lactic acid is not the end result and therefore does not ‘pool’ in your muscles after exercise. Lactic acid is converted to fuel. The word ‘acid’ probably started this myth, we associate pain with acid. There is no acid but the increase in acidity in your muscles is due to the release of hydrogen ions and can contribute to fatigue. The substance that can accumulate in muscles is instead, lactate. However, during and after your workout, your body can clear lactate by metabolizing it for energy to use later. The liver clears lactate from the bloodstream by converting it back into glucose or amino acids, the building blocks of proteins. High levels of lactate that exceed the clearance rate contribute to the sensation of tired muscles, and so the athlete must reduce her muscular effort. The liver can clear bloodstream lactate quicker in this scenario by the body undergoing methods to increase circulation. An active cool-down is helpful, along with active recovery modalities such as contrast therapy or the NormaTec Compression systems. I say active recovery because using these modalities is an active and intentional effort to promote recovery processes in the body as opposed to returning home or to work and sitting after an intense work-out, which prolongs the clearance process.
Recovery for CrossFit athletes means providing additional circulation following the high intensity exercises that produce lactate for more energy. Since the liver re-uptakes lactate from the bloodstream and converts it back to glucose or amino acids, expediting this process replaces glycogen stores for energy usage later or for muscle repair. Overall, CrossFit athletes can benefit from intentional recovery methods to improve performance.
2. Eccentric exercises in CrossFit
We discussed how lactate can contribute to the feeling of tired, unresponsive muscles, but neither lactate or lactic acid contribute to the muscle soreness that occurs one to two days after activity, otherwise known as delayed-onset muscle soreness or DOMS. The cause of DOMS is microscopic tears in the muscle and not a buildup of metabolic waste. Small tears are necessary for the growth of muscles but waiting for the microtrauma to repair feels like muscle soreness or stiffness and can limit performance. There is plenty of research that examines DOMS and the muscle contractions that bring about the most soreness in conditioned athletes. Amongst a concentric contraction (contracting while shortening, ie bicep curl), isometric contraction (contraction without movement, ie wall sits), and eccentric contraction (contracting while lengthening, ie RDL), eccentric exercise, or controlled elongation of the muscle, brings about the most myofibrillar disruption, disturbance of the extracellular matrix, and an inflammatory reaction in muscle cells - all of which results in DOMS. Second to eccentric is isometric contractions, but concentric contractions produced almost no responses contributing to DOMS. Olympic lifts such as deadlift and squat require eccentric contractions and are used in CrossFit programming frequently. Lengthening of a muscle can also occur when loads are lifted that are heavier than what the muscle can endure during its normal concentric contraction. Too much force will cause the muscle to lengthen instead of shorten. Because of this, a crucial time for recovery is after increasing weight or maxing out on weight.
Relief from DOMS come from the repair of microscopic tears, but that of course takes time. Icing and NSAIDS (ibuprofen) are both somewhat old-fashioned methods to ease the pain of DOMS, but more often than not, they will limit the healing phases. Stretching before and after an exercise has long been considered a good way to minimize soreness; however, recent research has shown the effect on DOMS is negligible. Methods that have shown to minimize soreness after workouts are any activities that increase blood circulation. Circulation is key in remodeling phases in order to bring a variety of metabolic substances to the muscle cells via the bloodstream. Proper recovery after eccentric-dominant activities can ensure skeletal muscle is repairing and forming healthy contractile muscle for continued power.
3. Metabolic stress, or varied movements, in CrossFit
Our bodies quickly adapt to exercise stressors. An important principle to know here is Wolff's Law of functional adaptation which states, "bones will adapt to imposed demands." This adaptation law can be applied to any tissue in the body. This is the reason why you may not feel sore after an activity. If you are a runner and only run for your exercise regimen, eventually muscle soreness is a rare occurrence because your body has become conditioned to this activity. This is because muscles adapt to stressors to avoid muscle damage and the consequences such as delayed-muscle onset soreness. However, even extremely well-conditioned athletes can still get DOMS. In well-conditioned athletes, DOMS is brought on from exercise variance. Variety keeps the body guessing and muscles are unfamiliar with the movements. The basis of CrossFit is variance to imitate training schedules of gymnasts, incorporating bodyweight exercises, Olympic lifts, and high intensity cardio. Constantly challenging the body and introducing new workout routines increases the prevalence of DOMS but in turn, contributes to faster muscle and cardiovascular development. During training when metabolic stress is at a maximum, recovery is important. But come competition time, the adaptations that occur help hit personal records.
What are the consequences?
A classic negative consequence of not training properly is overtraining. Overtraining can bring about physical and cognitive symptoms such as lack of energy, disinterest in activity, or injury. Chronically training on top of discomfort from DOMS or failing to allow the body to replenish depleted stores in high intensity training are fast contributors to overtraining. Cross-training and diet and nutrition in addition to active recovery can help prevent symptoms of overtraining.