Leisure and muscular performance in health and disease A study of 40-64-year-old northern Swedes.

Leisure and muscular performance in health and disease. A study of 40-64 year old northern Swedes. In Swedish, based upon f iv e reports in the English language. Björn Gerdle, Department o f Physical Medicine and R e h a b i l i ta t io n , Uni ver­ si ty of Umeå, S-901 85 Umeå, Sweden. Categories and frequencies of le isu re a c t i v i t i e s employed by 156 randomly selected males and females aged 40-44, 50-54, 60-64 were invest iga ted by structured in terv iews and were re la ted to le isu re s a t is fa c t io n , to exper­ ienced health and socio-economic s ta tus. In equal numbers (15) o f males and females from each group and in 24 males (60 +_ 6 years) with in te rm i t te n t c laud ica t ion (Cl) is o k in e t ic p lan ta r f le x io n performance was invest igated with re g is t ra t io n s of peak torque (PT), con tract iona l work (CW), act ive range-of-motion (RoM) and in tegra ted electromyograms from a l l threee t r i ­ ceps surae heads. Subjects performed a few maximum p lan ta r f lex ions at d i f ­ fe ren t v e lo c i t ie s of angular motion and also up to 200 consecutive p lan ta r f lex ions at 60°/s . The males aged 40-44 were re inves t iga ted a f te r two years a d d i t io n a l ly using electromyographic power frequency analyses. Leisure choice was mainly age and sex independent and extensive ly included outdoor a c t i v i t i e s . Leisure s a t is fa c t io n was p o s i t iv e ly associated with re ­ la t i v e frequency of a c t i v i t i e s . Symptoms o f bod i ly d iscomfort, in p a r t ic u ­ la r backpain, were qu ite common and apparently caused r e la t i v e ly low level of mutual le isu re a c t i v i t i e s . Thus, w i th in th is age span, le isu re a c t i v i ­ t ie s appear ra ther r ig id but often successfu lly , adhered to . Common a i l ­ ments in fluence partnersh ip m utua l i ty nega tive ly . P lantar f le x ion PT and CW are adequately pred ictab le by sex, age and crural c i rcumference. Uniformly a 3:2 male/female ra t io characterizes mechanical output and iEMG. The l a t t e r is ve lo c i ty independent. Output decreases with increasing age. Hence the ou tpu t /e x c i ta t io n balance (CW/iEMG) is age, but not sex, dependent. C I-pa t ien ts produce less PT and CW than do con tro ls . Independently o f th is disease, of age and sex, PT and CW describe pa ra l le l negative exponential functions of v e lo c i ty . During repeated manoeuvres p lan ta r f le x io n output and iEMG i n i t i a l l y drop, the re a f te r to maintain nearly s teady-state le v e ls . Throughout up to 200 contract ions CW/iEMG was unaltered in the c l i n i c a l l y healthy. T e s t / re te s t with two years in te rv a l y ie lded nearly iden t ica l re s u l ts . L e f t s h i f t s in mean power frequency in pa ra l le l with output-drop imply tha t the l a t t e r probably is due to FT-motor u n i t fa t ig u e . For CW, but not fo r PT, the drop became slower and the ( r e la t iv e ) s teady-state level higher with increasing age, in d ic a t in g s ig n i f i c a n t increase in endurance with age. In the Cl-pat ie n t s , ou tput, but not e x c i ta t io n , decreased a f te r a few r e p i t i t i o n s . Therefore, CW/iEMG f e l l d ram at ica l ly , imply ing in tramuscular fa t ig u e . Taken together with f ind ings of close associa tions between to ta l cumulated work and measured/expected maximum walking tolerance i t is suggested tha t mea­ surements of CW and ca lcu la t ions of CW/iEMG are o f c l i n i c a l value.