Like the age old question of the chicken or the egg, this is one of the questions asked of us at YEG Fitness most often. "Which should I do first, cardio or lift weights". While there is not set answer to this question, we look at the benefits of each and how they could help you with your fitness goals.
Doing cardio first can be beneficial as it will help warm you up for lifting. This has been shown in a recent study in the Journal of Strength and Conditioning to increase muscle strength. Also, if your goals are calorie burning, or increasing your cardio performance, you might want to make cardio your priority.
When lifting to gain strength and mass is your goal there is a generally accepted exercise order. Do your heaviest lifts first to build your greatest muscle gains. If this is true, then it should follow that you should do your cardio at the end of the workout. Your lifting should be affected less if you do cardio at the end of a workout since your muscles will be able to perform their best when they are not fatigued by a 45 minute session on the elliptical.
Most of the athletes we've talked to do whatever feels more natural to them. Most people get into a natural rhythm of doing cardio at the beginning or end of their workout as it's just a natural time for them or because it's the way they've always done it. This doesn't mean however that it's the most scientifically correct answer.
In the Journal of Strength and Conditioning study, participants were put on a four day per week workout schedule for two months. Half of the participants did cardio first while the other half did lifting. The cardio consisted of thirty minutes of a steady and moderately paced workout. The lifting session was a standard five or six exercises with three sets of eight to twelve reps per set.
The result.... Statistically insignificant differences. There was a slight trend in the strength gains seen by the group that did cardio first. The main drawback of this study is that it was performed on beginning lifters and we know that people beginning a workout program have their biggest gains at the beginning of their program.
Although the eight-week regimen yielded improvements in strength, cardio, and lean mass for everyone, it wasn't enough for a statistically significant difference between the groups. Interestingly, there did seem to be a trend toward greater strength in the group that did cardio first.
So right now, it looks like there is no real difference in the order of your workout. The one thing that is important is that you get out there and incorporate both cardio and lifting into your workout for the greatest gains towards your fitness goals.