Having spoken to many runners over the years, there's still a common misconception (although this is on the decline) that weight training will make a runner bulky, and therefore impair performance as effectively you're carrying around more bodyweight, thus increasing workload.
The evidence suggests that some training methods are favourable to runners as they promote increased strength without significant size gains. Low volume/high load sessions (typically performed in the off-season) and high volume/low load (normally carried out closer to race day) are examples of how to improve neuromuscular strength and strength endurance respectively, neither of which directly lead to weight gain.
Conversely, hypertrophy training (which involves high volume at a moderate load) actively encourages muscular growth and as runners we generally want to avoid such programmes. I'll go deeper into these approaches in a later article.
The point I want to make today, is that regardless of your training choices, you WILL put on unwanted bulk if you live in a calorie surplus. In other words, if you're taking on-board more calories than you're burning during your day, over time it doesn't matter what type of resistance training you're doing, you're going to put on weight.
Let's take high volume/low load training as an example which is very popular with runners. An individual could perform a workout with 3 sets of 15-20 repetitions of glute bridges, calf raises, bodyweight squats etc. The session in itself will not encourage an increase in size. This is in part due to low loads, but also as high repetitions performed at relatively low volumes (3 sets rather than 5 or 6) do not create enough stress to cause new muscle growth. Instead we improve our strength endurance with this session. However, what will ensure an increase in body mass is if more food is consumed than expended.
Of course, what kind of foods you eat will determine what part of your body composition changes. If you're eating lots of lean meat and vegetables whilst concurrently weight training, and you're in a calorie surplus, it's likely that some muscle mass will be gained. However, if donuts and crisps are mainly on the menu, then it'll be no surprise that fat stores which don't really provide any additional benefits past a certain point, will increase.
Ultimately, as runners we want to be strong relative to our size and have good strength endurance. Whilst sets, reps, load, rest periods etc can have an influence on our body mass and composition, the over-riding factor is how many calories are consumed over an extended period of time. If you're unsure about what you're currently taking on-board, and you'd like to keep track, the My Fitness Pal app is a very simple and effective way to keep a food diary. It will help ensure you consume the optimum amount of calories and the right balance of macronutrients for your goal. At the end of the day, we want our bodies working for, not against us.
By Marc Brown