Athletes looking to take their training to the next level and experience greater fitness improvements often do so by increasing their training volume. They typically do this by either expanding the duration of their workouts, or training more frequently. Both options allow athletes to work on multiple elements in a day. A longer training session means you can spend the first half working on gymnastic skills (as an example), some strength work, before finishing up with a metcon. Working out twice a day enables you to split the same workload between the two sessions. But is there one method that has a distinct advantage over the other?
Training less frequently allows for more recovery time between sessions
Proper recovery is crucial to becoming a fitter athlete. The time spent in rest is when the body can ‘repair’ the damage done through high intensity training. Muscle fibers are rebuilt and made stronger, lactic acid and other waste products are flushed from the system, and an athlete can give their central nervous system a break. Ensuring you have enough time to take care of all the elements of recovery puts you in the best position to have another great training session later on. The best option for proper recovery is through high volume, low frequency training—an athlete has more time to rest from one workout to the next. That’s not to say that people can’t recover well in-between multiple workouts in the same day, but it is tougher to experience the same level of recovery due to the shorter timeframe between workouts.
Shorter, higher frequency workouts are optimal for maintaining high-intensity
One of the biggest knocks against longer training sessions is that as the session drags on, the athlete becomes more and more fatigued. Their focus, intensity and desire to train may begin to wane. This is problematic, since training at a high intensity is shown to produce the most favorable adaptations (including fat loss, muscle growth, and increased aerobic and anaerobic capacity). Athletes have a better chance of maintaining high intensity during shorter workouts—after all, as time goes on, intensity levels drop. It is difficult to maintain a high heart rate and to endure high levels of lactic acid in the muscles for long periods of time.
What’s interesting is that multiple studies show how short workouts done at high intensity can be just as advantageous to cardiovascular adaptations as longer, endurance-style training sessions. A study published in the American Journal of Physiology found that individuals who did a sprint workout for 15 to 25 minutes three days a week were able to improve the structure and function of their arteries as much as individuals who exercised five days a week for 40 to 60 minutes at a moderate intensity. A 2008 study from the American Journal of Physiology: Regulatory, Integrative and Comparative Physiology compared VO2 max responses (the max amount of oxygen your body is capable of using, which also serves as a measure of your capacity for aerobic work and your potential as an endurance athlete) among male and female subjects who participated in an 8-week HIIT and a continuous cardiovascular training program. The HIIT program participants experienced a 15% increase to their VO2 max versus 9% for the aerobic training participants.
If you want to focus on cardiovascular endurance for a longer duration, you need a longer time frame in which to train it
A balanced training program should test an athlete’s fitness in multiple domains—including extended distances and or time domains. Consider that the athletes at the 2013 CrossFit Games had to complete a half-marathon row. Jason Khalipa and Samantha Briggs won that event with times of 1:18:02 and 1:27:47 respectively. It’s a safe bet to assume that the Games athletes train with workouts that have similar time domains—if not longer. That means they were exercising for over an hour straight. To be able to train the oxidative pathway effectively (a metabolic pathway that dominates low-powered activities that last for long periods), one must train for a sustained period of time—hence the need to occasionally include long duration workouts. You simply can’t go that long with the same intensity you’d employ for HIIT. Longer workouts that test the oxidative pathway help to build an aerobic base (which uses oxygen and primarily uses stored fat for energy), which is important in an athlete’s fitness (and for other sports/events they may choose to do outside of CrossFit).
Multiple workouts per day increases metabolism and keeps it raised for longer periods
During a workout, your body burns fat as a source of energy. Following the workout, your metabolism is raised and your body continues to burn fat for energy. So if you work out in the morning and in the evening, your metabolism will remain elevated for a prolonged period throughout the day and night, and you’ll reap the benefits of fat loss, improved blood pressure and increased energy (to name just three advantages of increased metabolism). High intensity interval training is effective at increasing post-exercise energy expenditure, referred to as Excess Post-exercise Oxygen Consumption (E.P.O.C.). A review study from the University of New Mexico explains EPOC as follows:
“Following an exercise session, oxygen consumption (and thus caloric expenditure) remains elevated as the working muscle cells restore physiological and metabolic factors in the cell to pre-exercise levels. This translates into higher and longer post-exercise caloric expenditure. In their review article, LaForgia, Withers, & Gore (2006) note that exercise intensity studies indicate higher E.P.O.C. values with HIIT training as compared to continuous aerobic training.”
Since athletes are able to maintain a higher intensity in shorter workouts, high frequency, low-volume training should be your preferred option for increasing your metabolism post-workout and throughout the day.
The best workout programs have a mix of high frequency and long duration
High frequency programming with short time frames are advantageous for training at a high intensity. This is key, because training at high intensity produces favorable adaptations including fat loss, muscle growth, and raised metabolism levels. Low frequency, long-duration workouts leave more time for recovery between training sessions. They also enable athletes to train the oxidative pathway through longer workouts that may not fit in a shorter time frame. An athlete’s individual schedule and goals will dictate which type of programming they favor, but if you’re looking to follow a constantly varied training regimen, try to include longer workouts alongside high frequency training weeks when possible.
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