What it's supposed to do: Train quadriceps, glutes, and hamstrings。
What it actually does: It often forces the spine to flex without engaging any of the necessary stabilization muscles of the hips, glutes, shoulders, and lower back。
A better exercise: Body-weight squats. Focus on descending with control as far as you can without rounding your lower back. Aim for 15 to 20 for a set and increase sets as you develop strength。
5. Squats Using Smith Machine 用史密斯机做深蹲
What it's supposed to do: Train chest, biceps, and legs。
What it actually does: The alignment of the machine—the bar is attached to a vertical sliding track—makes for linear, not natural, arched movements. This puts stress on the knees, shoulders, and lower back。
A better exercise: Body-weight or weighted squats. See "Seated Leg Press" above。
6. Roman Chair Back Extension 背部伸展练习器(罗马椅)
What it's supposed to do: Train spinal erectors。
What it actually does: Repeatedly flexing the back while it's supporting weight places pressure on the spine and increases the risk of damaging your disks。
A better exercise: The bird-dog. Crouch on all fours, extend your right arm forward, and extend left leg backward. Do 10 seven-second reps, and then switch to the opposite side。