The chest and shoulder muscles are both used in many of the same compound movements such as the bench press or military press. Training either the chest or shoulders on one day, then on the next day training the other muscle group, may result in a decrease in performance in the muscle trained on day two.
Training Shoulders First
Training your shoulders to fatigue may result in a decrease in strength and intensity of your chest workout the next day. Although you are not directly training your chest on shoulder day, your shoulders will come into play during compound exercises such as the bench press or dumbbell press and especially in incline bench press exercises. The muscle soreness following weight training known as delayed onset muscle soreness can also affect your performance. DOMS typically occurs 24 to 48 hours after a workout and can last up to five days, note Jack H. Wilmore and David L. Costill, authors of "Physiology of Sport and Exercise." If your front deltoids are sore or fatigued from the previous day's workout, your bench press or chest workout may suffer. Wait an extra day or two to allow your shoulders more recovery time before training your chest.
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Always train your weaker muscle area first in your workout plan when you are fresh. Training shoulders first in your weekly workout routine is acceptable, as long as your chest is not the weaker muscle area. If your shoulders are strong and well developed, and your chest lags behind, train your chest first your in weekly training program and shoulders two or three days later. This will allow you to devote all of your energy and focus to the muscle group that needs the most work.
Training Chest with Shoulders
Because the shoulders aid the chest in movements such as the bench press or dips, it may be beneficial to train them on the same day. It takes a muscle about seven days to fully recover from a workout, notes Karen Sessions, NSCA-CPT. Combining the two muscles together in the same workout will maximize training for both the shoulders and the chest, so neither muscle suffers. Moreover, both muscle groups will be able to have a full week of recovery before retraining. Because your chest muscles are larger than your shoulders, perform chest exercises first in your routine followed by shoulder exercises. However, train the shoulders first in your routine if your shoulders are your weaker muscle area.
Shoulder and Chest Workout
Begin your workout with heavy compound exercises, prior to training the individual muscle groups. Complete one or two warmup sets on the bench press, using to light to moderate weight in which you can complete 12 to 15 repetitions. Once warmed up, perform two to three working sets of six to 10 repetitions, resting two to three minutes between sets. Following the bench press, perform three sets of eight to 12 repetitions of incline dumbbell press, Arnold press, bent over lateral raise, flat dumbbell flys and cable crossovers, resting one to two minutes between each set.