Functional Resistance Training for the Leg, Foot, and Ankle

By Dr. Jennifaye V. Brown

I often classify exercise as what I teach clients/patients to do to improve impairment at the body structure function level often targeting joint range of motion and muscle strength. Gains in joint flexibility and muscle strength through isometric, concentric or eccentric force generation is based on the position of the body part in open or closed chain and whether resistance is placed close to or far from the joint and or muscle insertion or origin. There are many strategies to optimize the impairment at the body structure function level and it is usually very easy to target 1 joint and the muscles that cross that joint.

However, to improve impairment at the activity level as it relates to function, for example sit to stand and vice versa, squatting or side stepping, requires a myriad of moving parts which have to be prioritized in order to get an effective outcome. Astute rehab practitioners need to engage in movement analysis and then determine where to put the resistance to improve the functional outcome. Movement analysis is the key, but how often do we break down a functional task and work through the phases of muscle activity and the joint motion requirements, let alone background activity such as postural control and the position of the head?

Both approaches are needed, but for participation in life roles, functional resistance training at the activity level should be optimized by considering the person, task and the environment. The literature looks at functional resistance training for the leg ankle and foot through a different lens depending on the impairment and how it impacts the targeted outcome (highest level of function would be walking or running), and for the scope of this article, the focus will be on a neurological injury from stroke. What is common in musculoskeletal and upper motor neuron injuries is the use of progressive resistance high-intensity exercises.^1-6 What makes the treatment approach different is that individuals with stroke have multi-system involvement such as cognition, vision, sensory, neuromuscular and musculoskeletal involvement and automatic as well as reactive postural control has to be considered for functional movement involving the extremities.⁶ And in current stroke literature, the focus is on external agents to either facilitate movement and strengthen that movement through resistance or produce movement due to the lack of force generation from upper motor neuron damage.^3,7

In a study by Swaminathan et al using soft leg exosuit with cables and hardware to determine force output and resistance provided through the system, force generation was improved during push off for individuals with chronic stroke.³ This body of research revealed that participants demonstrated a significant and clinical meaningful increase in propulsion force production based on low, medium and slow speeds of walking on a treadmill and those gains in gait kinetics were sustained after the resistance was removed.³ Furthermore, as resistance from the exoskeleton varied, once trained the paretic ankle generated enough force to meet the resistance.³  What makes this research viable to replicate in clinical practice is that the focus was on a meaningful task (walking), that was specific to the person (resistance applied based on the amount of force that muscles could generate) and the environment was conducive for training (walking at self-selected speeds then increasing or decreasing based on muscle activity on a treadmill). If one wants to walk faster you have to train faster given the context of viable muscle activity in which neurons not damaged from the infarct are solicited in the penumbra. For the training effect and outcome needed to improve function, we are often NOT properly dosing to activate those spared neurons, not only in the neurologic diagnosed population but those with isolated musculoskeletal injuries impacting the leg and the foot.^8-10

Practitioners often state that the research is often unrelatable and impossible to mimic in clinic—it has no practical application. Based on the research by Swaminathan et al, I have decided to demonstrate the fundamentals principles targeting the leg, foot, and ankle using a treadmill and elastic bands.³ It is not that difficult. Sometimes, we need to get back to the basics and be creative in treatment. Stay tuned!

Jennifaye V. Brown, PT, MSPT, PhD, NCS, CAPS is an American Physical Therapy Association 4-time 10-year board certified neurologic physical therapist in Charleston, South Carolina, specializing in stroke rehabilitation, specifically gait analysis and treatment, AFO design, and the redesign of lived spaces allowing individuals with disAbilities to age in place. She is the author of the book, Brace Yourself: Everything You Need to Know About AFOs After Stroke. Visit her YouTube channel @jvbneuropt for more information regarding stroke rehabilitation.