Symptoms and Quadriceps Fatigability after Walking and Cycling in Chronic Obstructive Pulmonary Disease

Abstract

Patients with chronic obstructive pulmonary disease (COPD) may stop cycling due to leg effort rather than breathlessness. However, cycling is not relevant to many patients, although walking may be more familiar. A total of 84 patients with COPD were asked to name the predominant symptom limiting incremental shuttle walking, endurance shuttle walking, incremental cycle ergometry, and endurance cycle ergometry, performed to exhaustion on four separate days. Furthermore, quadriceps fatigability was evaluated in 12 patients by measuring unpotentiated and potentiated twitch quadriceps tensions before and 30 minutes after incremental walking and cycling. Breathlessness alone was a more commonly cited limiting symptom after incremental walking compared with incremental cycling (81 vs. 34%; p < 0.001) and after endurance walking compared with endurance cycling (75 vs. 29%; p < 0.001). In addition, there was no significant change in mean pre- and postwalking twitch quadriceps tensions. However, cycling produced a significant reduction (unpotentiated 7.42 +/- 2.22 vs. 6.48 +/- 2.09 kg [p < 0.001]; potentiated 10.19 +/- 3.99 vs. 8.45 +/- 3.18 kg [p < 0.001]). Pre- to postexercise changes were significantly greater during cycling compared with walking (unpotentiated p = 0.01; potentiated p = 0.003). Leg effort is an infrequent symptom after walking in COPD, and low frequency fatigue of the quadriceps is an infrequent feature of incremental walking.

Benefits of Physical Training in Sarcoidosis

“…Regardless, the between-groups differences in both variables were significantly greater in the group completing the intervention. Because there is lack of clarity [38], future studies are needed to address the issue of which exercise modality (cycle ergometry, walking, or both) should be used to assess the effects of interventions aimed at improving physical functional capacity.…”

Recommendations on the use of exercise testing in clinical practice

“…The mode of exercise testing may be important. It appears that walking induces a greater degree of arterial desaturation than cycling [54,86,88,286]. The 6-MWT has previously been shown to be sensitive to the administration of supplemental oxygen [287,288].…”

“…While desaturation may occur with any type of intense leg exercise, walking either on a treadmill or freely along the ground elicits more hypoxaemia than cycleergometry [54,[86][87][88]. Any of the standardised walk tests is suitable for diagnosing desaturation [11].…”

“…For example, MAN et al [88] showed in COPD patients that leg effort assessed by subjective scoring on a Borg scale is a frequent symptom during incremental and endurance cycleergometry, but infrequent during incremental and endurance walking. This would imply that interventions targeted specifically at the skeletal muscles should preferably be evaluated by cycle-ergometry and not by walking tests.…”

Exercise and dyspnoea in COPD

“…It was proposed that factors that determine peripheral skeletal muscle performance, such as oxygen delivery during exercise and the presence of peripheral muscle weakness [16], were at least as important as variables related to lung mechanics in determining exercise performance in COPD. These observations stimulated considerable debate, although more recent reports in smaller populations of wellcharacterised patients with very severe COPD indicate that, in most cases, breathlessness limited exercise rather than leg fatigue [17]. An explanation for this discrepancy has now been provided in a mechanistic study in which exercise during treadmill walking was compared with that during cycle exercise [18].…”