The data are obtained within an RCT study. The primary aim of the present study was to examine the effect of a plantar intrinsic foot muscle strengthening training versus no training on maximum gait speed in older adults who are involved in a functional exercise program. To investigate the trainability of the intrinsic foot muscles and how this translates into improved mobility , the secondary aim was to examine the effect of the training on foot and ankle biomechanics during gait, comfortable gait speed, step length, balance during gait, intrinsic foot muscle capacity, isometric toe flexor strength, self-reported mobility impairments, physical activity, fall incidents, concerns about falling and physical functioning. The collected data consist of baseline characteristics and data collected before and after the 12 week foot muscle strengthening training.

Data files READ ME_STIFF_RCT_data processing pipeline SHORT.pdf Data meetformulieren merged with allProcessedData.sav Statistical output: Output_ANCOVA and assumptions_lab data.spv Output_ANCOVA and assumptions_physical activity.spv Output_ANCOVA and assumptions_quistionnaires.spv Output_ANCOVA effect modification binary.spv Output_demographics.spv Output_descriptives lab data.spv Output_descriptives lab data_group difference in change.spv Output_descriptives questionnaires.spv

Scripts: ANCOVA met effect modifiers binary.sps ANCOVA.sps Calculate Change from Baseline.sps Demographics.sps Descriptives Lab data.sps Descriptives questionaires.sps OverallAdherence.sps RecodeSF36.sps

Structure data package READ ME_STIFF_RCT_data processing pipeline SHORT.pdf

Method Data were collected pre- and post-intervention by questionnaires and by measurements in the movement analysis laboratory. At baseline, the physical activity was measured over a period of 7 days and subsequently summarized. In the laboratory, ultrasound images were taken from the foot muscles to obtain morphological measures during post-processing. Toe strength was measures by a pressure plate while pushing down as hard as possible. Balance during comfortable gait was assessed by recording the body’s center of mass and center of pressure and calculating the margin of stability. Gait parameters (i.e., spatiotemporal measures and foot- and ankle biomechanics) were assessed by walking at comfortable and fast gait speed while infrared markers attached to the foot and lower leg were tracked. Extensive post-processing procedures resulted in the gait parameters. Universe Older adults who were involved in a group-based functional exercise program were in and around the city of Eindhoven, The Netherlands. Eligible for participation were individuals 1) aged 65 years or older, 2) able to walk 10 m without using a walking aid, 3) involved in a functional exercise program delivered to a group of older adults by an educated or certified physical therapist or instructor, 4) reporting to have either concerns about falling or to have experienced a fall in the previous 12 months or to have difficulties with mobility, gait or balance in daily life. Excluded from participation were individuals reporting presence of any disorder interfering with adherence to the program or with the execution of foot exercises. Country / Nation Eindhoven, The Netherlands.