I get asked all of the time by clients, family members, friends, and acquaintance about what they should do first, cardio or weights. Well, unfortunately, the answer isn’t clear cut. Ultimately, you have to ask yourself, “What are my exercise goals? Do I need to focus my attention on improving my aerobic capacity or increasing my strength?” In an ideal world, most of us would love to be in excellent cardiorespiratory shape AND very strong and muscular looking. Unfortunately, in the real world, science has proven we can’t have our cake and eat it, too. We’ll discuss this shortly.

First, how do we incorporate both aerobic exercise (AE) and strength training (ST) into our exercise routines. There are several ways we can do this:

  1. We can do both AE and ST within the same workout.
  2. We can split up AE and ST and do them at different times of the day, such as AE in the morning and ST in the evening.
  3. We can do AE and ST on completely different days, such as AE on Monday and ST on Tuesday.
  4. We can do AE and ST workouts and different points of one’s training cycle, such as establishing an aerobic base at the beginning of the training cycle and increasing maximal strength and power at the end of the training cycle.

Research has found if AE is done before ST this results in an increase in aerobic power and an increase in post-exercise energy expenditure. Unfortunately, due to the fatigue of similar muscle groups used in AE as in ST, the quality of the ST workout decreases, unless you increase recovery time between bouts of AE and ST. The positive results of doing AE first may benefit those who are looking to specifically improve their aerobic performance such as endurance athletes like marathon runners and triathletes.

Doing ST before AE has resulted in more benefits. It may not be too difficult to understand why, when ST is performed before AE, muscular strength, power, and hypertrophy (muscle growth) increases. As mentioned before, an ST workout will be of higher quality because the muscles are not fatigued compared with doing AE first. One interesting finding of doing ST prior to AE has been the increase in fat metabolism during the subsequent AE. So, if you want to burn more body fat during your workouts lift weights before you get on the treadmill or go out for your run. In two particular demographics where doing ST prior to AE has been found to be more beneficial has been in women and the elderly (>65 years of age). In both populations, aging-related muscle mass loss results in decreased VO2 max (measurement of aerobic fitness). When these populations participated in ST prior to doing AE, the aforementioned increases in stength, power, muscle growth resulted in increased aerobic capacity. Developing more muscle mass can help you improve you aerobic capacity.

In summary, if you’re asking yourself if you should do cardio before weights or vice versa, first determine what you’re trying to achieve. If you’re training to run a 5k, 8k, 10k, half- or full-marathon or plan on doing triathlons, you may want to focus much of your time on getting in your runs, seat time on the bike, and laps in the pool while complementing your endurance workouts with strength training. Endurance athletes who strength train can not only prevent injuries, but it can also improve performance. Now, if you’re a strength and power athlete or a women or elderly person looking to maintain or improve your functional capacity, research has proven that pumping iron first and complementing your workout with aerobic exercise is more beneficial.