Plantar Kinetics During Wheeled Knee Walker Use Compared to Different Assistive Walking Devices in Persons With Type 2 Diabetes Mellitus.

Background: Diabetic patients with foot ulcers are commonly prescribed assistive walking devices to unload the affected foot and promote tissue healing. However, the effect on shear loads to the contralateral foot is unknown. This study investigated the effect of a wheeled knee walker (WKW), compared to common devices, on compressive and shear plantar forces carried by the propulsive foot during walking in patients with type 2 diabetes mellitus. A secondary objective investigated plantar forces' correlations with body weight unloaded (BWU). Methods: Participants walked a maximum of 200 m per condition during normal walking or when using crutches, a standard walker, and a WKW in randomized order. Plantar forces were measured with force plates, and wireless force-sensitive pads measured BWU through the hands. The WKW was instrumented to measure BWU onto the seat and handlebars. Three-dimensional motion capture confirmed gait events. Results: The WKW produced the lowest vertical, braking, propulsive, and medial shear forces but the highest lateral shear force among all conditions. Using crutches or a walker had negligible medial and lateral shear (mean = -6.69 N and -7.80 N), with normal walking producing the highest medial shear. There was a poor relationship between BWU and assistive walking devices and shear force values. Conclusion: A WKW could be the preferred assistive device for unloading a diabetic foot ulcer. The magnitude of lateral force would need further investigation to determine ulceration risk, given patient susceptibility and neuropathy. Clinical Relevance: Understanding shear forces on the propulsive foot is important for minimizing contralateral limb tissue damage risk while treating an ulcer. Different assistive walking devices change walking patterns and affect shear forces on the plantar surface of the foot. Although the WKW minimizes several loading metrics, a clinical trial investigating assistive walking device compliance and wound healing in diabetic foot ulcer patients across devices is needed.

Ketone Bodies Impact on Hypoxic CO2 Retention Protocol During Exercise.

Exogenous ketone esters have demonstrated the capacity to increase oxygen availability during acute hypoxic exposure leading to the potential application of their use to mitigate performance declines at high altitudes. Voluntary hypoventilation (VH) with exercise reliably reduces oxygen availability and increases carbon dioxide retention without alterations to ambient pressure or gas content. Utilizing a double-blind randomized crossover design, fifteen recreational male distance runners performed submaximal exercise (4 × 5 min; 70% VO2 Max) with VH. An exogenous ketone ester (KME; 573 mg⋅kg-1) or iso-caloric flavor matched placebo (PLA) was consumed prior to exercise. Metabolites, blood gases, expired air, heart rate, oxygen saturation, cognition, and perception metrics were collected throughout. KME rapidly elevated R-ß-hydroxybutyrate and reduced blood glucose without altering lactate production. KME lowered pH, bicarbonate, and total carbon dioxide. VH with exercise significantly reduced blood (SpO2) and muscle (SmO2) oxygenation and increased cognitive mean reaction time and respiratory rate regardless of condition. KME administration significantly elevated respiratory exchange ratio (RER) at rest and throughout recovery from VH, compared to PLA. Blood carbon dioxide (PCO2) retention increased in the PLA condition while decreasing in the KME condition, leading to a significantly lower PCO2 value immediately post VH exercise (IPE; p = 0.031) and at recovery (p = 0.001), independent of respiratory rate. The KME's ability to rapidly alter metabolism, acid/base balance, CO2 retention, and respiratory exchange rate independent of respiratory rate changes at rest, during, and/or following VH exercise protocol illustrates a rapid countermeasure to CO2 retention in concert with systemic metabolic changes.