Effects of Aerobic Exercise Therapy through Nordic Walking Program in Lactate Concentrations, Fatigue and Quality-of-Life in Patients with Long-COVID Syndrome: A Non-Randomized Parallel Controlled Trial

Long-COVID syndrome comprises a variety of signs and symptoms that develop during or after infection with COVID-19 which may affect the physical capabilities. However, there is a lack of studies investigating the effects of Long-COVID syndrome in sport capabilities after suffering from COVID-19 infection. The purpose of the study was to evaluate and compare lactate concentration and quality of life (QoL) in patients with Long-COVID with those who have not developed non-Long-COVID during Nordic walking exercise therapy. Twenty-nine patients (25.5 ± 7.1 years) took part in a non-randomized controlled trial, divided into two groups: a Long-COVID group ( = 16) and a non-Long-COVID control ( = 13). Patients were confirmed as having Long-COVID syndrome if they experienced fatigue or tiredness when performing daily activities and worsening of symptoms after vigorous physical or mental activity. All participants underwent a 12-week Nordic Walking program. Lactate concentration after exercise and distance covered during all sessions were measured. Pre- and Long-Nordic Walking program, the Modified Fatigue Impact Scale (MFIS), the Short Form 36 Health Survey (SF-36), and EURO QoL-5D (EQ-ED) were administered to assess fatigue and quality of life, respectively. There was a lactate concentration effect between groups (F = 5.604; = 0.024). However, there was no significant effect as a result of the session (F = 3.521; = 0.121) with no interaction of group × session (F = 1.345; = 0.414). The group main effect (F = 23.088; < 0.001), time effect (F = 6.625; = 0.026), and group × time (F = 4.632; = 0.002) interaction on the SF-36 scale were noted. Also, there were a significant group main effect (F = 38.372; < 0.001), time effect (F = 12.424; = 0.005), and group × time interaction (F = 4.340; = 0.014) on EQ-5D. However, there was only a significant group main effect (F = 26.235; < 0.001) with no effect on time (F = 2.265; = 0.160) and group × time (F = 1.584; = 0.234) interaction on the MFIS scale. The Long-COVID group showed higher lactate concentration compared with the control group during the 12 weeks of the Nordic Walking program. The Long-COVID group presented a decrease in fatigue with respect to the control group according to the MFIS scale, as well as improvement in quality of life after aerobic exercise therapy.