METHODSĪfter the baseline scan, participants were returned to a seated position with their feet on the floor. Therefore, the purpose of our study was to quantify intrinsic plantar foot muscle activation as measured by T2 MRI after 4 specific exercises. Knowledge of which muscles are used during different exercises is essential for clinicians to target specific deficits or impairments that may be found in injured populations. Using a technique that can provide a more comprehensive analysis of muscle activity within the intrinsic foot muscles is crucial for determining which muscles are contracting during specific exercises. 2, 17 However, limited evidence describes specifically which intrinsic foot muscles are targeted by different exercises. Several exercises that are currently prescribed for the rehabilitation of acute and chronic foot and lower extremity conditions are thought to improve intrinsic foot-muscle function. To our knowledge, this technique has not been used previously to assess activation patterns of the intrinsic foot muscles. 20– 22 The use of T2 MRI allows for a noninvasive assessment of individual muscle activation. Muscle functional magnetic resonance imaging (MRI) has been used to quantify changes in T2 signal intensity on the basis of hemodynamic, metabolic, and mechanical changes that are directly related to neuromuscular activation of muscle tissue. The smaller number of muscles analyzed during these studies may not represent the foot core system 2 as a functional unit. 9 However, it is difficult to confirm into which muscle an electrode has been inserted, and thus, researchers often use ultrasonography 5, 9 to ensure fine-wire placement. 19 Intramuscular EMG with fine-wire electrodes has been used to observe activation and minimize crosstalk of the abductor hallucis, flexor digitorum brevis, and quadratus plantae during gait. Surface electromyography 4, 6, 13, 18 (sEMG) has been used to describe activation of the abductor hallucis, flexor digitorum brevis, and quadratus plantae, but the small sizes and close proximity of these muscles increase the risk for crosstalk from adjacent and underlying muscles. Unfortunately, literature describing the individual activation levels for most of the intrinsic foot muscles during specific exercises is lacking.
![intrinsic vs extrinsic foot muscles intrinsic vs extrinsic foot muscles](https://image1.slideserve.com/2361556/muscles-of-foot-l.jpg)
Rehabilitation and strengthening of these muscles are used to treat these conditions, 1, 2, 17 and prophylactic exercises targeting the intrinsic foot muscles may aid in injury prevention. 8– 11 Several conditions, such as plantar fasciopathy, 1, 3, 6 hallux valgus, 12– 14 and pes planus, 1, 12, 15, 16 are associated with weakened or atrophied intrinsic foot muscles.
![intrinsic vs extrinsic foot muscles intrinsic vs extrinsic foot muscles](https://musculoskeletalkey.com/wp-content/uploads/2016/08/F500170f11-06b-9780323086844.jpg)
The extrinsic foot muscles primarily provide osteokinematic movements, 1, 2 whereas the intrinsic foot muscles maintain the medial longitudinal arch, 3– 6 control the degree and velocity of arch deformation, 7 and aid in postural control during stance and gait. The foot is an intricate structure consisting of a complex network of bones, ligaments, and muscles that work synchronously to maintain its shape and allow movements such as walking and running.