RESUMEN
INTRODUCTION: Whereas deficits in muscle function, particularly power production, develop in old age and are risk factors for mobility impairment, a complete understanding of muscle fatigue during dynamic contractions is lacking. We tested hypotheses related to torque-producing capacity, fatigue resistance, and variability of torque production during repeated maximal contractions in healthy older, mobility-impaired older, and young women. METHODS: Knee extensor fatigue (decline in torque) was measured during 4 min of dynamic contractions. Torque variability was characterized using a novel 4-component logistic regression model. RESULTS: Young women produced more torque at baseline and during the protocol than older women (P < 0.001). Although fatigue did not differ between groups (P = 0.53), torque variability differed by group (P = 0.022) and was greater in older impaired compared with young women (P = 0.010). CONCLUSIONS: These results suggest that increased torque variability may combine with baseline muscle weakness to limit function, particularly in older adults with mobility impairments.
Asunto(s)
Envejecimiento/fisiología , Limitación de la Movilidad , Contracción Muscular/fisiología , Fatiga Muscular/fisiología , Debilidad Muscular/fisiopatología , Torque , Adulto , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos/fisiología , Evaluación de la Discapacidad , Femenino , Estado de Salud , Humanos , Articulación de la Rodilla/fisiología , Modelos Biológicos , Análisis de RegresiónRESUMEN
The Indian leafwing butterfly Kallima paralekta (Horsfield, 1829) (Nymphalidae) is an Asian forest-dwelling, leaf-mimic. Genome skimming by Illumina sequencing permitted assembly of a complete circular mitogenome of 15,200 bp from K. paralekta consisting of 79.5% AT nucleotides, 22 tRNAs, 13 protein-coding genes, two rRNAs and a control region in the typical butterfly gene order. Kallima paralekta COX1 features an atypical CGA start codon, while ATP6, COX1, COX2, ND4, ND4L, and ND5 exhibit incomplete stop codons completed by 3' A residues added to the mRNA. Phylogenetic reconstruction places K. paraleckta within the monophyletic genus Kallima, sister to Mallika in the subfamily Nymphalinae. These data support the monophyly of tribe Kallimini and contribute to the evolutionary systematics of the Nymphalidae.