Explosive Resistance Training Increases Rate of Force Development in Ankle Dorsiflexors and Gait Function in Adults With Cerebral Palsy

Abstract

Kirk, H, Geertsen, SS, Lorentzen, J, Krarup, KB, Bandholm, T, and Nielsen, JB. Explosive resistance training increases rate of force development in ankle dorsiflexors and gait function in adults with cerebral palsy. J Strength Cond Res 30(10): 2749-2760, 2016-Alterations in passive elastic properties of muscles and reduced ability to quickly generate muscle force contribute to impaired gait function in adults with cerebral palsy (CP). In this study, we investigated whether 12 weeks of explosive and progressive heavy-resistance training (PRT) increases rate of force development of ankle dorsiflexors (RFDdf), improves gait function, and affects passive ankle joint stiffness in adults with CP. Thirty-five adults (age: 36.5; range: 18-59 years) with CP were nonrandomly assigned to a PRT or nontraining control (CON) group in this explorative trial. The PRT group trained ankle dorsiflexion, plantarflexion, leg press, hamstring curls, abdominal curls, and back extension 3 days per week for 12 weeks, with 3 sets per exercise and progressing during the training period from 12 to 6 repetition maximums. RFDdf, 3-dimensional gait analysis, functional performance, and ankle joint passive and reflex-mediated muscle stiffness were evaluated before and after. RFDdf increased significantly after PRT compared to CON. PRT also caused a significant increase in toe lift late in swing and a significantly more dorsiflexed ankle joint at ground contact and during stance. The increased toe-lift amplitude was correlated to the increased RFDdf (r = 0.73). No other between-group differences were observed. These findings suggest that explosive PRT may increase RFDdf and facilitate larger range of movement in the ankle joint during gait. Explosive PRT should be tested in clinical practice as part of a long-term training program for adults with CP.

FAST CP: The effect of Functional Anaerobic and Strength Training on muscle properties, functional capacity, and gait in adolescents and young adults with Cerebral Palsy

“…The finding that GPS did not change following training is an important result to show that individuals with CP can perform high intensity anaerobic training and heavy PRT without a deterioration in their gait.In contrast to our findings, Kirk et al146 reported increased ankle DF during toe lift, at foot contact, and during stance following explosive PRT in adults with CP. The increased rate of force development of the ankle DF muscles reported following the 12-week training program could account for the improved ankle joint kinematics during gait 146. The main difference between Kirk et al's146 PRT intervention design compared to our study and that of Taylor et al,…”

“…An increased rate of force development in the DF muscles, as well as greater range of ankle joint movement during gait has been reported previously following PRT in adults with CP, supporting the notion that PRT of the lower extremity muscles can improve gait outcomes in this population. 146 The change in PF strength in young adults with CP in this study was significantly associated with changes in their functional strength test score (R 2 =0.32) and six-minute walk test distance (R 2 =0.28). This finding indicates that an increase in PF strength underpinned a significant proportion of the improvement in functional capacity outcomes.…”

“…(explosive) during the concentric phase of each repetition. Participants in our FAST training intervention were required to lift explosively for the final four weeks of the program, however this may have been insufficient training volume to induce adaptations similar to those reported by Kirk et al 146 The improved ankle joint kinematics following explosive PRT reported by Kirk et al, 146 did not however translate to any improvements in overground functional capacity measures.…”

“…43,45,57,159 One recent quasi-controlled study implemented a lower limb explosive PRT program in adults with CP and reported increased rate of force development in ankle DF muscles, as well as an increase in ankle DF during toe clearance and at foot contact. 146 There were no posttraining differences found however, in functional capacity measures (6MWT; 10m walk test; timed up and down stairs test) between the training and control groups. Individuals with CP have difficulties with co-ordination and motor control, therefore, providing resistance training as an isolated intervention may not enhance motor learning or translate to improvements in walking ability.…”

“…145 Similarly in adults with CP, improvements in ankle DF function and range of movement during gait has been shown following explosive resistance training. 146 Although the adult CP literature is scarce regarding the relationship between PF strength and function, taken together, these findings suggest that muscle strength may play a key role in effective mobility and functional capacity in adults with CP as they age.…”