If you're trying to increase your overall strength while building lean muscle mass, you've got to start training with the TRX suspension trainer [1]. The suspension trainer is one of the most diverse pieces of equipment in the gym — you can work every muscle group with it [2], and the best part is, your body is the weight. Because of this, not only will you strengthen and define your muscles [3], but you will also improve the overall functional movement patterns that you do day in and day out, like pushing, pulling, twisting, bending, and squatting.

One of the best pulling exercises you can do with the TRX is the deltoid fly [4], working your shoulders, core (the stabilizer), and back. This shoulder-strengthening exercise [5] will also improve your posture by opening up your shoulders and strengthening your upper back.

Here's how to do it:

• Before getting started, make sure the TRX suspension trainer is secured to an anchor point (a fixed object that won't move and can support you weight). The straps should be at mid-length.
• Grab the handles with each hand and walk your feet out approximately two feet away from your body. Your arms should be extended in front of you and your body should be in a straight line. The further you walk your feet in front of you, the more challenging the exercise will become.
• With your core engaged, open your arms out toward the sides, like you're making a "T" with your arms. Be sure to keep tension on the straps throughout the entire movement.
• With your core still engaged and tension on the straps, return to the starting position with control. This counts as one rep.
• Complete three sets of 12 reps.