Adaptive Cycling: Classification, Adaptations, and Biomechanics

Increased awareness, recognition, and accessibility has led to an increase in the popularity of adaptive cycling. This article aims to provide up-to-date information for clinicians about available adaptations, participation options, and resources. We review the para-cycling classification system and 4 main categories of cycles. There are multiple considerations for fit and customization depending on an individual's disability to improve efficiency and comfort. Virtual platforms that allow riders to train and compete online have grown in popularity among para-cycling communities and offer an alternative to riding outdoors. Many national and local organizations offer communities and grants to assist with adaptive equipment.

Novel M4 positive allosteric modulators derived from questioning the role and impact of a presumed intramolecular hydrogen-bonding motif in β-amino carboxamide-harboring ligands

This letter describes a focused exercise to explore the role of the β-amino carboxamide moiety found in all of the first generation M₄ PAMs and question if the NH₂ group served solely to stabilize an intramolecular hydrogen bond (IMHB) and enforce planarity. To address this issue (and to potentially find a substitute for the β-amino carboxamide that engendered P-gp and contributed to solubility liabilities), we removed the NH₂, generating des-amino congeners and surveyed other functional groups in the β-position. These modifications led to weak M₄ PAMs with poor DMPK properties. Cyclization of the β-amino carboxamide moiety by virtue of a pyrazole ring re-enforced the IMHB, led to potent (and patented) M₄ PAMs, many as potent as the classical bicyclic β-amino carboxamide analogs, but with significant CYP1A2 inhibition. Overall, this exercise indicated that the β-amino carboxamide moiety most likely facilitates an IMHB, and is essential for M₄ PAM activity within classical bicyclic M₄ PAM scaffolds.