Why might this be?
Rachel Straub, PhD, an exercise physiologist and the co-author of Weight Training Without Injury: Over 350 Step-by-Step Pictures Including What Not To Do!, explains that improvements in strength from resistance training come from both increased neuromuscular adaptations and increases in muscle size (hypertrophy).
“During the early phase of strength training (approximately the first month), improvements in strength result primarily from improvements in neural drive, as hypertrophy does not become a dominant contributor until week three to five,” says Dr. Straub. Since this study only lasted four weeks, it’s likely the gains seen were predominantly due to neural adaptations.
These adaptations are what allow your brain to recruit more muscle fibers in a coordinated, efficient fashion, resulting in a more forceful muscle contraction. “The more frequent sessions provide more frequent neural stimulations, with adequate rest,” says Dr. Straub. And when the brain receives a stimulus more often, changes occur more readily.
Doing short strength training workouts every day rather than one or two long workouts per week provides other benefits as well. “If you strength train only once a week, fatigue limits your performance and there is a long delay in the training stimulus,” explains Dr. Straub. “However, if you strength train daily, you can alter your focus (such as one day lower body versus another day upper body), so fatigue becomes less of a limiting factor.”
So what should your weekly routine look like?
With this in mind, if you are going to aim for regular strength training workouts, skip the full-body sessions and zero in a particular body part each day in order to give your muscles adequate rest. (Generally speaking, you should take 48 to 72 hours between workouts that target the same muscle groups.)
“The American College of Sports Medicine advises split body workouts for advanced strength training, which is defined as four to five days per week,” notes Dr. Straub. “Total-body workouts are most appropriate if you are strength training less frequently (two to three days per week).”
For the upper body, Dr. Straub suggests training the biceps, triceps, back, chest, shoulders. On lower body days, she suggests focusing on the hamstrings, quadriceps, and glutes. “The core could be incorporated on both days, or either day,” she adds.
When determining the loads you should use and the number of reps you should do for each exercise, Dr. Straub says you need to consider your primary goal. For instance, performing very few reps at maximal eccentric strength is ideal for increasing muscular strength and size. But if your goal is to increase muscular endurance, focus on using light loads with high reps (more than 15) and very little rest. Either way, she says, “if the last one to three reps of any set are not challenging, the load is too light.”
Here’s an example of how you could structure a week of mini strength training workouts: