If the goal is to increase strength on a particular exercise, that exercise should unquestionably be performed first in the workout,[1] as performing the exercise in an unfatigued state will allow the individual to lift heavier loads, which is of the utmost importance for maximizing gains in strength.
In terms of muscle gain, the overall body of evidence suggests muscle gain does not differ between programs that start workouts with a multi-joint exercise followed by a single-joint (SJ) exercise and programs that start workouts with a single-joint exercise followed by a multi-joint (MJ) exercise.[1] However, the results of this meta-analysis are limited by the fact that most studies measured changes in muscle size only in the muscle that was the primary agonist in the single-joint exercise, but functioned as a synergist or supporting muscle in the multi-joint exercise. For example, a few studies measured changes in biceps brachii size between a group that performed workouts of a lat pulldown followed by a biceps curl and a group that performed workouts of a biceps curl followed by a lat pulldown.
The results indicated that changes in biceps brachii size are similar between groups, but what about changes in latissimus dorsi size? Does regularly performing a biceps curl before a lat pulldown compromise increases in latissimus dorsi size? This question has not been adequately examined, but limited evidence suggests that this may indeed be the case.
A 2020 study not included in the aforementioned meta-analysis compared changes in the cross-sectional area (CSA) of the pectoralis major in a group that performed workouts consisting of the barbell bench press followed by the lying barbell triceps press (MJ+SJ) and a group that performed workouts consisting of the lying barbell triceps press followed by the barbell bench press (SJ+MJ).[2] Although there was technically no significant difference between groups, pectoralis major growth in SJ+MJ was approximately half that of MJ+SJ (5.6% vs. 10.6%).
This result may be due to the fact that the triceps brachii functions as a synergist in the bench press. Thus, performing the lying barbell triceps press first in the workout fatigued the triceps brachii and consequently impaired subsequent bench press performance, reducing the hypertrophic stimulus attained by the pectoralis major.
Further research is needed, but the same rule of thumb for strength likely applies to muscle gain: the exercise most important to the primary goal of the training program should be performed first in the workout. For example, if the individual’s primary goal is to increase the size of their chest, they should start their workout with an exercise where the chest muscles are the primary agonist, whether that be a multi-joint (e.g., barbell bench press) or a single-joint exercise (e.g., a machine chest fly).