Age-graded reductions in quadriceps muscle strength and peak aerobic capacity in COPD / Reduções graduadas por idade na força muscular do quadríceps e no pico de consumo de oxigênio na DPOC

BACKGROUND: Reductions in quadriceps strength and peak aerobic capacity (VO2) in patients with chronic obstructive pulmonary disease (COPD) have been studied in relatively small samples over a short period. Moreover, results were not corrected for confounding variables, such as lean muscle mass, gender, and gas transfer capacity of the lungs. OBJECTIVES: To compare quadriceps muscle strength and peak V.O2 in women and men while stratifying for age and gas transfer capacity. We then corrected for lower-limb lean muscle mass to see whether and to what extent the age-graded reduction remained evident. METHODS: Retrospectively, data of 374 women and 593 men with COPD were analyzed: lung function, current drug therapy, quadriceps strength, peak V.O2, lower-limb lean muscle mass, and gas transfer capacity. RESULTS: Quadriceps strength and peak V.O2 were lower in older women and men with a gas transfer capacity of <50% predicted, also after adjustment for lower-limb lean muscle mass. Moreover, quadriceps strength and peak V.O2 were lower in older women and men with a gas transfer capacity of <50% predicted, also after adjustment for lower-limb lean muscle mass. Moreover, quadriceps strength and peak V.O2 were related to age in COPD, particularly in women and men with a gas transfer capacity of >50% predicted. Yet, counter to our hypothesis, lower-limb lean muscle mass did not show an age-graded reduction and, in turn, could not account for the relationship of age with quadriceps strength and peak V.O2. CONCLUSIONS: It is apparent that there is an age-graded reduction in skeletal muscle function in patients with COPD. Therefore, prevention of an age-graded decline in quadriceps muscle strength and peak V.O2 may need to become an outcome of pulmonary rehabilitation of patients with COPD.

CONTEXTUALIZAÇÃO: As reduções da força do quadríceps e do pico de consumo de oxigênio (V.O2) em pacientes com doença pulmonar obstrutiva crônica (DPOC) são estudadas em amostras relativamente pequenas e por curto período de tempo. Além disso, os resultados não são corrigidos por variáveis confundidoras, como conteúdo de massa magra, gênero e capacidade de difusão pulmonar. OBJETIVOS: Comparar a força muscular do quadríceps e o pico de V.O2 em mulheres e homens estratificados por idade e capacidade de difusão pulmonar e, então, corrigir pela massa magra dos membros inferiores para verificar se e até que ponto a redução graduada por idade permaneceu evidente. MÉTODOS: Retrospectivamente, foram analisados dados de 374 mulheres e 593 homens com DPOC, referentes a: função pulmonar, tratamento medicamentoso, força do quadríceps, pico de V.O2, massa magra dos membros inferiores e capacidade de difusão pulmonar. RESULTADOS: A força muscular do quadríceps e o pico de V.O2 foram menores em idosos com capacidade de difusão pulmonar <50% do previsto, mesmo após correção pela massa magra dos membros inferiores. Além disso, a força do quadríceps e o pico de V.O2 correlacionaram-se com a idade, especialmente em homens e mulheres com capacidade de difusão >50% do previsto. No entanto, a massa magra dos membros inferiores não demonstrou redução graduada por idade e não justificou a relação da idade com a força do quadríceps e o pico de V.O2, contrariando a nossa hipótese. CONCLUSÕES: Aparentemente, há uma redução graduada por idade na função musculoesquelética em pacientes com DPOC. Portanto, a prevenção do declínio graduado por idade na força do quadríceps e no pico de V.O2 deveria ser um objetivo da reabilitação pulmonar em pacientes com DPOC.

Age-graded reductions in quadriceps muscle strength and peak aerobic capacity in COPD.

BACKGROUND: Reductions in quadriceps strength and peak aerobic capacity (VO2) in patients with chronic obstructive pulmonary disease (COPD) have been studied in relatively small samples over a short period. Moreover, results were not corrected for confounding variables, such as lean muscle mass, gender, and gas transfer capacity of the lungs. OBJECTIVES: To compare quadriceps muscle strength and peak V.O2 in women and men while stratifying for age and gas transfer capacity. We then corrected for lower-limb lean muscle mass to see whether and to what extent the age-graded reduction remained evident. METHODS: Retrospectively, data of 374 women and 593 men with COPD were analyzed: lung function, current drug therapy, quadriceps strength, peak V.O2, lower-limb lean muscle mass, and gas transfer capacity. RESULTS: Quadriceps strength and peak V.O2 were lower in older women and men with a gas transfer capacity of <50% predicted, also after adjustment for lower-limb lean muscle mass. Moreover, quadriceps strength and peak V.O2 were lower in older women and men with a gas transfer capacity of <50% predicted, also after adjustment for lower-limb lean muscle mass. Moreover, quadriceps strength and peak V.O2 were related to age in COPD, particularly in women and men with a gas transfer capacity of >50% predicted. Yet, counter to our hypothesis, lower-limb lean muscle mass did not show an age-graded reduction and, in turn, could not account for the relationship of age with quadriceps strength and peak V.O2. CONCLUSIONS: It is apparent that there is an age-graded reduction in skeletal muscle function in patients with COPD. Therefore, prevention of an age-graded decline in quadriceps muscle strength and peak V.O2 may need to become an outcome of pulmonary rehabilitation of patients with COPD.

Comparison of daily physical activity between COPD patients from Central Europe and South America.

BACKGROUND: In healthy elderly and adults, lower physical activity level in daily life has been associated with lower socio-economic level and non-Caucasian race. The objective of this study was to determine if this is also applicable in chronic obstructive pulmonary disease (COPD) by comparing physical activity levels in daily life in stable patients from two countries (Austria and Brazil) with different socio-economic and ethnic characteristics. METHODS: Physical activity in daily life was objectively assessed in 40 Austrian and 40 Brazilian COPD patients. Groups were matched for age, gender, body mass index, disease severity, smoking history, presence of concomitant heart disease, lung function, dyspnea and functional exercise capacity. In addition, climatic conditions were similar during the period of data collection in the two groups. RESULTS: In comparison to Brazilian patients, Austrian patients had a significantly lower walking time (p=0.04), higher sitting time (p=0.02) and lower movement intensity (p=0.0001). The proportion of patients who did not reach an average of 30min of walking per day was 48% in the Austrian group and 23% in the Brazilian group. CONCLUSIONS: Austrian patients with COPD showed a significantly lower daily physical activity level in comparison to matched Brazilian patients. Socio-economic and ethnic factors appear to influence stable COPD patients differently than described in previous studies including healthy subjects.