The study will investigate changes in certain locomotor parameters as early predictors of disease in smokers who are prone to develop chronic obstructive pulmonary disease (COPD).

The research will include about 150 respondents aged 40-65, smokers and non-smokers, and will be conducted at the Special Hospital for Medical Rehabilitation 'Daruvarske toplice'. All patients will make spirometry and the Tiffeneau-Pinelli index (ratio of forced expiratory volume in 1 second - FEV1 and forced vital capacity FVC).

All patients will be maesured: body weight, height, BMI (body mass index), waist circumference, pulse (cp), saturation (SpO2), blood pressure, respiratory index and thoracic spine mobility index measured. The thickness of the skin fold will be measured on the abdomen with a caliper and on the measuring device for the analysis of body mass composition - Gaia, the percentage of muscle and fat tissue will be determined for each patient, as well as the analysis of body mass composition. All patients will do a 6-minute walk test and the patient's cardiorespiratory and muscular ability will be tested on a bicycle erogometer, the values of maximal oxygen uptake (VO2 max) and pulse (cp) will be recorded and the patient's fitness status determined. Each patient will estimate dyspnea intensity from 1 -10 before and after a 6-minute walk test and before and after a bicycle ergometer according to the Borg's dyspnea scale. The strength test of the the quadriceps muscle, will be measured in all patients on the Biodex isokinetic device. Quadriceps strength testing will be performed on 2 occasions. On one occasion without medication, except those that the patient may take permanently, and on the other 90 minutes after the patient takes 1 tbl of L - Arginine 500 mg on mouth to an empty stomach ,in order to monitor the possible increase in quadriceps strength. All patients who are smokers will have recorded : the age of onset of smoking, the year of smoking experience and the average number of cigarettes smoked per day. All patients will complete the CAT, IPAQ and DASS-21 questionnaire.

Inclusion Criteria:

• aged 40-65
• smokers and non-smokers, All patients will make spirometry and the Tiffeneau-Pinelli index (ratio of forced expiratory volume in 1 second - FEV1 and forced vital capacity FVC)> 75% of the predictive value will be taken as an inclusion criteria.

Exclusion Criteria:

• FEV1 / FVC <75%,
• inflammatory rheumatic diseases,
• malignancies,
• acute and severe heart or lung disease,
• unregulated hypertension,
• patients who have undergone major surgery in the past year,
• patients with implanted hip, knee or ankle prosthesis, will be excluded from the study.