The heel touch exercise is a common bodyweight movement in core routines, performed by lying on your back with knees bent and reaching the hands toward alternating heels. This movement is a variation of a crunch that incorporates a side-to-side rocking motion. Concerns often arise that this exercise, and similar ones targeting the sides of the torso, could lead to a widening of the waistline. This fear centers on the possibility of building up the oblique muscles, making the midsection appear thicker instead of leaner.
Core Muscles and Their Function
The abdominal wall is composed of several muscle layers, each with a distinct role in movement and stability. The Rectus Abdominis is the most superficial muscle running vertically down the front of the torso, often called the “six-pack” muscle. Its primary function is to flex the spine, bringing the ribcage and pelvis closer together during a traditional crunch.
The muscles most relevant to the concern about widening are the obliques, which lie on the sides of the torso. The External Obliques are the outermost layer, enabling the trunk to twist and bend laterally. Located beneath them, the Internal Obliques work with the external layer to facilitate rotation and side bending. Their growth (hypertrophy) is the source of the common fear regarding waist size.
The Mechanics of the Heel Touch Exercise
The heel touch exercise is designed to engage the side muscles, involving a slight lift of the shoulders combined with lateral flexion and rotation of the trunk. This movement actively recruits the external and internal obliques as the hand reaches for the heel on the same side.
The exercise requires a short range of motion, and resistance comes only from the weight of the upper body. Because the heel touch uses only body weight, it is considered a low-intensity exercise compared to movements using heavy external resistance, such as weighted side bends. The primary focus is to isolate and contract the obliques through a gentle rocking motion. Bodyweight exercises rarely provide the high mechanical tension necessary to stimulate significant muscle growth.
Muscle Hypertrophy and Waist Size
Muscle hypertrophy, or the increase in muscle size, requires specific training conditions that heel touches do not meet. Significant growth depends on progressive overload, meaning consistently increasing the tension or resistance placed on the muscle over time. This is typically achieved through lifting heavy weights or performing high-volume resistance training to the point of muscular fatigue.
The obliques are prone to hypertrophy when subjected to heavy resistance and high volume, such as in powerlifting or bodybuilding training. However, the light resistance and short range of motion of the standard heel touch are more likely to build muscular endurance and tone rather than bulk. For the average person, the level of muscle damage and metabolic stress is insufficient to prompt the substantial growth that would visually widen the waist.
The circumference of the waist is primarily determined by the amount of visceral and subcutaneous body fat stored in the midsection. Even if the obliques experience a small amount of growth, this increase is visually insignificant compared to the effect of body fat. If a person’s waist appears to be increasing while exercising, the most common reason is an overall calorie surplus leading to fat accumulation, not muscle gain from light core work.
Developing the obliques through light exercises like heel touches can lead to a more defined and stable core. These exercises contribute to a stronger foundation, which can improve posture and spinal support. The fear that heel touches will noticeably broaden the waist is a common misconception, as the exercise lacks the necessary resistance and volume to cause significant muscle expansion.