Study on Impact of Maximal Strength Training in Patients With COPD

Exercise intolerance is a cardinal problem existing in patients with Chronic Obstructive Pulmonary Disease (COPD). Moreover, skeletal muscle dysfunction is a common extra-pulmonary manifestation, leading to fatigue, decrease in activity of daily living (ADL) performance and quality of life and increase of risk of falls, mainly in older patients. In the context of pulmonary rehabilitation, recent guidelines and metanalysis describe that Resistance Training (RT) can be successfully performed alone or in conjunction with Endurance Training (ET) without evidence of adverse events.

As concern the RT programs, metanalysis in COPD describe that training have been mainly performed with the lower limbs and the training intensities are heterogeneous, generally ranging from 40% to 70% of 1-Repetition Maximum (1-RM).

Maximal Strength Training (MST) is a RT typically performed at ~85-90% of 1RM with maximal velocity to be developed in the concentric phase. Recent literature indicates a significant amelioration on the Rate of Force Development (RFD) after MST in healthy subjects, post-menopausal woman and older populations.

When comparing to the conventional ET, MST generates a little change in muscle mass (no hypertrophy), but a much greater improvement in the RFD. It has been described that neural adjustments play a major role in the MST-induced adaptations. MST is also well documented to improve aerobic endurance by improving walking work efficiency.

Although the mechanisms at the base of MST effect on the mechanical efficiency have not been completely clarified, there is evidence that changes in the relationships between power and speed bring to a longer relaxation phase inside the cycle of job, improving the recovery between contractions.

In this field, only a small cohort study of COPD patients was conducted describing that MST can meaningfully improve the strength and the RFD, with an increase of around 32% for mechanical efficiency and a decrease of the perceived effort during submaximal job. This improvement could determine best performances in daily activities and a best quality of life. Nevertheless, this study has been conducted only in a small cohort (twelve patients) of patients with COPD and further studies are necessary to define the impact on the different components that determine the effort intolerance.

The main aim of this physiological pilot randomized controlled trail will be to test the feasibility and the efficacy of the MST compared to standard ET on strength, effort tolerance, fatigue, economy of walking, dyspnea and risk of falls in a populations of COPD patients, in a short and middle term (6 months).

Inclusion criteria

• COPD clinical definition according to GOLD guidelines with forced expiratory volume (FEV1)/ forced vital capacity (FVC) < 70%, and FEV1 < 50% of predicted
• stable clinical condition

Exclusion criteria

• pulmonary diseases other than COPD
• type II diabetes or other metabolic diseases
• malign disease
• a respiratory tract infection within the last 4 wks
• long oxygen therapy use.