Concurrent aerobic and strength training program in post-COVID adult patients

Dear Editor,

Analysing the accumulated experience of previous coronavirus epidemics and the current COVID-19, the physical limitations of survivors are and will be a significant part of the medical practice of rehabilitation specialists.¹ To ensure optimal physical recovery of these patients, specific rehabilitation programmes have been designed over the last year. The aim of the present study is to analyse changes in symptomatology and functionality in survivors of COVID-19 with decreased physical capacity after an eight-week physical training programme.

Out of 134 patients who required rehabilitation treatment during admission for COVID-19, 122 were assessed two months after discharge using: symptomatology (fatigue and subjective dyspnoea), 6 Minute Walk Test (6MWT), Sit to Stand Test in 30 s (STST), Quick Disabilities of Arm, Shoulder and Hand (QuickDASH), dynamometry of both hands and Hospital Anxiety and Depression Scale (HADS). Twenty-six patients with poorer functional capacity were selected (<500 m in 6MWT, <19 in the STST and without prior severe cognitive or functional impairment) to conduct a quasi-experimental study between September 2020 and September 2021, before and after a combined eight-week programme of aerobic exercise (30 min on a cycle ergometer or walking) and strength (two sets of 10–12 repetitions of eight muscle groups, at moderate intensity, 3–4 according to the modified Borg scale of perceived exertion), along with strengthening the respiratory muscles. They trained three days a week in person along with home recommendations to complete at least three days of aerobic endurance and two days of strength training per week.

A sample of 16 (61.5%) men with a mean age of 59.73 (standard deviation [SD] 6.92) and body mass index of 32.09 (SD 4.43) was obtained, with 24 (96%) being right-handed. They were admitted for a mean of 35.88 (SD 27.71) days and 18 (69.23%) required a mean stay in the intensive care unit of 14.92 (SD 15.69) days.

The data before and after the training program are detailed in Table 1.

Table 1.

This table shows the absolute frequencies (percentage) and means (standard deviation) of the data collected before and after the combined training programme and their statistical significance. A p < 0.005 is considered to be of statistical significance.

Variables	Value (n 26)
	Before training	After training	p
Fatigue	21 (80.76%)	5 (19.23%)	0.008
Subjective dyspnoea	12 (46.15%)	4 (15.38%)	0.019
6-Minute Walk Test (6MWT)	383.15 (SD 73.02)	459.58 (SD 78.70)	<0.001
Sit to Stand Test (STST)	10.69 (SD 3.51)	14.73 (SD 5.24)	<0.001
QuickDASH Questionnaire	36.14 (SD 23.43)	36.06 (SD 20.95)	0.988
Right hand dynamometry	27.01 (SD 10.35)	33.99 (SD 11.48)	<0.001
Left hand dynamometry	24.04 (SD 9.46)	29.43 (SD 8.96)	<0.001
Anxiety Questionnaire (HADS-A)	7.81 (SD 3.79)	6.96 (SD 4.42)	0.279
Depression Questionnaire (HADS-D)	6.31 (SD 4.29)	5.46 (SD 3.81)	0.378

SD, standard deviation; HADS-A, Hospital Anxiety and Depression Scale — Anxiety; HADS-D, Hospital Anxiety and Depression Scale — Depression; QuickDASH, Quick Disabilities of Arm, Shoulder and Hand.

The literature supports early initiation of rehabilitation during hospital admission for SARS-CoV-2 infection, but it should not be forgotten that functional recovery at later stages is also a primary goal, with physical exercise being a mainstay.² Although there are no common protocols, the little scientific evidence available promotes rehabilitation programs similar to ours in post-COVID-19 patients after hospital discharge, including aerobic, strength, balance and respiratory rehabilitation exercises.^1,2 An increasing number of studies are integrating strength into health-oriented training programmes, including respiratory diseases, as it enhances the effects of aerobic exercise.³

Referring to post-viral symptoms, Halpin et al. highlight the relationship between asthenia, dyspnoea and exercise intolerance, so that a training programme could have an impact on improving fatigue and dyspnoea, as we observed in our study.⁴

We have also observed significant improvement in 6MWT, STST and dynamometry in both hands. Taking into account the similarities with other coronaviruses, we highlight the study by Lau et al. in which they also observed an improvement in 6MWT after aerobic and strength training in person compared to recommendations by telephone, at hospital discharge for SARS-COV-1.¹ The STST is a shorter alternative to the 6MWT for measuring lower limb physical capacity and strength and is sensitive to changes after rehabilitation in patients with chronic obstructive pulmonary disease, a property relevant to our study.³ Concerning the upper limbs, we have observed improvement in hand grip strength, and it has been reported that dynamometry values are directly related to overall muscle strength and lung function.⁵ However, the QuickDASH score has barely changed, and this may be related to the high frequency of shoulder pain in these patients.⁴

We have observed no improvement in the anxiety and depression scale, possibly because it requires a multidisciplinary approach and a longer time to show changes.

The main limitation of our study is the absence of a control group.

We conclude that an eight-week programme of concurrent aerobic and strength training in post-COVID survivors improves symptoms, fatigue and dyspnoea, as well as functional capacity measured by 6MWT, STST and grip strength in both hands.

Funding

This research has not received specific funding from public or private sector agencies or non-profit organisations.

Conflict of interests

The authors declare that they have no conflict of interest.

Acknowledgements

Special thanks to all health workers for their work, dedication and sacrifice during this health crisis. Our gratitude to Pedro Beneyto Martín for the statistical support.