Department of Physical Education, Purdue University, West Lafayette, Indiana, U.S.A. ABSTRACT

Transcription

1 36 EFFECTS OF EXERCISE ON FREE SERUM CHOLESTEROL D. L. MONTGOMERY, Ph.D.* and A. H. ISMAIL, Ph.D. Deparmen of Physical Educaion, Purdue Universiy, Wes Lafayee, Indiana, U.S.A. ABSTRACT Two age groups (young and old, n = 12) mached for physical finess and wo physical finess groups (high and old, n = 12) mached for age paricipaed in a four monh physical finess programme. Blood samples were drawn a four sages of meabolic sress a he pre-es and five sages a he pos-es. The blood samples were analyzed by calorimeric mehods for oal choleserol and free choleserol. Saisical analysis revealed ha: (1) Shor-erm exercise increased oal choleserol, free choleserol, and he percen free choleserol from he resing sae o he submaximal and maximal exercise saes. (2) There was no change in free serum choleserol from he pre- o pos-ess. (3) The high-fi group, compared wih he low-fi group, had a lower free choleserol level bu had similar percen free choleserol values. (4) There was no significan difference beween age groups for eiher oal serum choleserol, free choleserol, or he percen free choleserol levels. INTRODUCTION The associaion of hyperlipidemia wih he aheroscleroic process is well documened in a wide range of experimenal animals (Clarkson, 1963) and in man (Friedman, 1969). Wih increasing choleserol concenraion, here is an increased risk of coronary hear disease. There is no evidence of a criical level of serum choleserol which separaes high from low risk individuals. Compared wih oher species, man has a high concenraion of oal choleserol (Goodman, 1965). The percenage of free choleserol usually does no change significanly even when he oal choleserol level is considerably alered (Goodman, 1965). Free choleserol makes up abou one-hird of he oal serum choleserol, while he remaining wo-hirds is eserified wih fay acids (Goodman, 1965). Since free choleserol is more aherogenic han choleserol eser (Lacko e al, 1972), he percenage of free serum choleserol in conjuncion wih he oal choleserol concenraion is an imporan facor in he developmen of aherosclerosis. I appears ha physical aciviy will reduce serum choleserol levels when here is a corresponding decrease in he percenage of body fa weigh (Campbell, 1966, 1968; Monoye e al, 1959; Tooshi, 1971). Also, habiually acive populaions have lower serum choleserol levels han sedenary populaions (Casdorph, 1972; Faulkner e al, 1969; Karvonen e al, 1961; Lowensein, 1964). The purpose of he presen invesigaion was o observe he effec of a four-monh programme on he oal, free, and percen free serum choleserol levels in high and low finess groups mached for age and weigh, and in young and old age groups mached for physical finess and weigh. METHODS Tweny-four men ranging in age from 24 o 65 years, were seleced on he basis of age, weigh and physical finess level from 100 men who paricipaed in he physical finess programme a Purdue Universiy, consising of calishenics, jogging, and recreaional aciviies such as baskeball, volleyball, swimming, squash, and handball. The 24 men were seleced so ha here was a young group (n = 12) and an older group (n = 12) which were mached for weigh and physical finess. In addiion, he same 24 men were divided ino wo physical finess groups using he es crierion of Ismail e al, (1965), a 'low-fi' group and a 'high-fi' group (n = 12). The wo finess groups were mached for age and weigh. All subjecs had clinically normal serum glucose: 70 o 120 mg% (Harleco), and riglyceride: 30 o 200 mg% (Oxford), levels. The subjecs were esed a he beginning and a he end of he four-monh finess programme. Venous blood samples were drawn a four sages of meabolic sress: res, submaximal exercise (10 minues of readmill walking a 3 m.p.h. wih he elevaion increased by 2% every 2 minues), maximal exercise (running on a readmill a 6 m.p.h. wih he elevaion increased by 2% every 2 minues), and recovery, (15 minues of res following he readmill run). On he pos-es, wo blood samples were drawn during maximal exercise, wih he firs *Presen Address for correspondence: David L. Mongomery, (Assisan Professor), Dep. of Physical Educaion, McGill Universiy, 475 Pine Avenue Wes, Monreal, Quebec, H2W 1S4, Canada.

2 blood sample aken a he same sress ha corresponded o he pre-es. The second blood sample was obained o reflec he new maximal level. The biochemical variables were measured by colorimeric mehods. Serum riglycerides were measured according o Oxford Laboraories Procedure.* Serum glucose levels were measured according o a Harleco Procedure.** The oal choleserol and free choleserol concenraions were measured by he Hycel Mehod.*** Daa were analyzed by a facorial analysis of variance wih subjecs grouped by age-finess groups. The Newman-Keuls analysis was used for mean comparison whenever he analysis of variance resuls yielded significance a a minimum of 0.10 level. RESULTS The means and sandard errors of he variables used o selec he age and finess groups are presened in * Tri-glyceride deerminaion, 'Tri-Chol Principle', Oxford Laboraories, Foser Ciy, Cal. ** Glucose deerminaion, Harleco Inc., Philadelphia, Pen. *** Choleserol deerminaion, Hycel Inc., Houson, Tex. Selecion Variable Age (yrs.) Pre Tes Physical Finess Score Pre-Tes Pos-Tes Weigh (kg) Pre-Tes Pos-Tes ing Serum Glucose (mg%) Pre-Tes Pos-Tes ing Serum Triglyceride (mg%) Pre-Tes Pos-Tes * (0.01 level, 1 1 df) = Table 1. The young and old groups were mached for weigh and physical finess. The high-fi and low-fi groups were mached for weigh and age. Boh age groups and boh finess groups improved significanly in physical finess level from he pre- o he pos-ess. The glucose levels were similar for boh he young and old groups and he high-fi and low-fi groups. There was a significan difference in resing serum riglyceride levels beween he high-fi and low-fi groups. The means and sandard errors of he oal serum choleserol, free choleserol, and percen free choleserol for he wo age groups and he wo finess groups are presened in Tables 11, Ill and IV, respecively. The percen free choleserol values were obained by: Free Choleserol x 100= Percen Free Choleserol Toal Choleserol For he hree biochemical variables, a paern isshown saring wih a resing mean value ha increases during submaximal exercise, followed by furher increases during maximal exercise and decreases during he 15- minue recovery period. Table V shows he analysis of variance for he serum oal choleserol, free choleserol and percen free cho- TABLE / Pre- and Pos-Programme Tes Values (X and S.E) of he Selecion Variables for he Age and Finess Groups (n = 12) Age Groups Old 36.8 ± ± ± ± * 80.8 ± ± i ± ± ± ± ± * 76.9 ± ± ± ± ± ± Finess Groups High-Fi Low-Fi 44.4 ± ± ± ± * 77.7 ± ± ± ± ± ± ± ± * 80.0 ± ± ± ± ± ±

3 38 TABLE II Pre- and Pos-Programme Values (X and S.E.) of he Serum Toal Choleserol a Seleced Meabolic Levels for he Age and Finess Groups (n = 12) Meabolic Level Age Groups Finess Groups Pre Tes Pos Tes I ± ± ± ± ± ± ± ± ± 19.8 Old High-Fi Low Fi ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 18.1 TABLE Ill Pre- and Pos-Programme Values (X and S.E) of he Free Serum Choleserol a seleced meabolic levels for he Age and Finess Groups (n = 12) Meabolic Level Pre Tes Pos Tes I 59.0 ± ± ± ± ± ± ± ± ± 5.8 Age Groups Old TABLE IV 54.3 ± ± ± ± ± ± ± ± ± 1.7 Finess Groups High-Fi Low-Fi 51.6 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 4.9 Pre- and Pos-Programme Values (X and S. E) of he Percen Free Serum Choleserol a seleced meabolic levels for he Age and Finess Groups (n = 12) Meabolic Level Age Groups Finess Groups Old High Fil Low-Fi Pre Tes Pos Tes I 24.5 ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± 0.7

4 leserol. The ANOVA echnique was used o deermine he significan changes, if any, beween finess groups (high versus low), beween age groups (young versus old) beween ess (pre versus pos), beween meabolic sages (res, submaximal, maximal and recovery), and beween he ineracions of he various facors. For each of he hree biochemical variables, wo ANOVA ables are presened in Table V. The firs ANOVA able uilizes he maximal I level of exercise, while he second ANOVA able uilizes he maximal 11 level of exercise. On he pre-es, here was only maximal I exercise, whereas on he pos-es, maximal I exercise corresponded o he same exercise level as in he pre-es, while maximal 11 exercise indicaed he new maximal level. A he pos-es, maximal I exercise acually represened a high submaximal exercise level. I is necessary o presen wo ANOVA ables for each biochemical variable so ha he degrees of freedom for he F ess would no be ficiious as would be he case if five meabolic levels were used and maximal I was repeaed in he pre-es o correspond wih maximal 11 in he pos-es. For oal chleserol, he effec of meabolic levels was significan a he 0.01 level. There was a significan increase in serum oal choleserol from he resing sae of he submaximal exercise, and a furher significan increase during maximal exercise wih a significan decrease during he recovery period. The ineracion of ess by meabolic sages (TM) was significan a he 0.10 level. In he pos-es, he resing serum oal choleserol was lower han a he pre-es whereas a all oher sages of exercise, he pos-es oal choleserol concenraion was higher han he pre-es oal choleserol concenraion. The ineracion of finess groups by meabolic sages (FM) was significan a he 0.10 level using he meabolic sages ha included maximal I exercise bu was no significan using he meabolic sages ha included maximal 11 exercise. The significan ineracion using maximal I exercise bu insignifican ineracion using maximal 11 exercise was possibly relaed o he amoun of ime run on he readmill by he high and low finess groups. The longer he ime run on he readmill, he more ime ha is allowed for lipids o be mobilized from he issues. Since he high-fi group compared o he low-fi groups (15.40 min. versus 5.67 min.) ran for a longer ime on he readmill during maximal I exercise in comparison wih maximal 11 exercise (17.88 min. versus min.), he mean differences beween finess groups were more apparen in FM using maximal I han in FM using maximal 11 exercise. The differences in serum oal choleserol beween he low-fi group and he high-fi group were smaller during maximal I exercise in comparison wih he oher meabolic sages, which resuled in a significan ineracion a maximal I exercise in Table V. The oal choleserol responses a maximal ABLE V Analysis of Variance for Serum Toal Choleserol, Free Choleserol, and Percen Free Choleserol Source of Variaion Finess Groups (F) 1 Age Groups (A) 1 Tess (T) 1 Meabolic Levels (M) 3 FXA 1 FXT 1 AXT 1 FXM 3 AXM 3 TXM 3 Subjecs 20 Three Facor Ineracion Three Facor Ineracion Five Facor Ineracion Degrees of Freedom Toal Choleserol Fa Fb e c C e d a Using meabolic levels,, Max - I, and. b Using meabolic levels,, Max - II, and. c Saisically significan a he 0.10 level. d Saisically significan a he 0.05 level. e Saisically significan a he 0.01 level. Free Choleserol Fa Fb 3.71C e C e % Free Choleserol Fa Fb d l1 d

5 40 exercise were dependen upon he finess level which deermined he subjecs' olerance o sress. The effec of meabolic levels was significan a he 0.01 level for free serum choleserol and a he 0.05 level for percen free choleserol. There was a significan increase in free choleserol in he serum from he resing concenraion o he submaximal exercise, wih a furher increase during maximal exercise, and a significan decrease during he recovery period. The percen free choleserol a res was significanly lower han he percen free choleserol during exercise and during he recovery period. Acue exercise increased boh he absolue and he percen free choleserol. The high-fi group in comparison o he low-fi group had a significanly (P < 0.10) lower free choleserol. However, here was no significan difference in percen free choleserol beween he wo finess groups. DISCUSSION Long duraion exercise can aler he serum choleserol level because choleserol can be degraded by he oxidaion of is side chain o carbon dioxide (Chaikoff e al, 1952; Myan & Lewis, 1966). Side chain oxidaion of choleserol is increased during exercise in man (Malinow & Perley, 1969) and in ras (Malinow e al, 1968). There is some evidence ha serum choleserol levels can be reduced by decreasing body weigh (Campbell, 1966, 1968; Faulkner e al, 1969; Lowensein, 1964; Mock, 1972; Monoye e a, 1959; Teraslinna, 1966; Wa e al, 1972; Zauner, 1970). Generally, in overweigh individuals here is a loss in body weigh as a resul of a long-erm exercise programme so ha exercise may indirecly be associaed wih he decrease in serum oal choleserol level. Since here was no significan reducion in body weigh in he 24 subjecs in his sudy, his finding could explain why here was no significan change in serum oal choleserol concenraion from he pre- o pos-ess. In his sudy he high-fi group, in comparison o he low-fi group, had a significanly lower free choleserol concenraion. In he design of he sudy, he wo finess groups were mached for weighs, however here was a significan difference beween he high-fi and low-fi groups in erms of he percenage lean body weigh. A pre-es, he high-fi group was 86.3% lean and he low-fi group was 80.0% lean. Monoye e a, (1974) have repored a significan posiive correlaion beween oal choleserol and body faness as measured by he sum of four skinfolds in 4000 subjecs aged 10 o 64 years. Thus, he difference in percen lean body weigh beween he wo finess groups may have conribued o he significan difference beween he wo groups. Habiual exercise over several years by he high-fi group could possibly explain he differences. In man, he lecihin-choleserol acylransferase (LCAT) enzyme caalyzes he ransfer of fay acids from he 3-posiion of lecihin o free choleserol in he plasma (Glomse, 1962; Glomse e a, 1962; Sperry, 1935). Since human plasma does no conain enzymes ha hydrolyze choleserol esers, he eserificaion of free choleserol represens he aciviy of LCAT. The effec of shor-erm exercise in his sudy, increased he oal choleserol, free choleserol and percen free choleserol. During he recovery period, he oal choleserol and boh he absolue and percen free choleserol decreased. Since here was an increase in oal lipid mobilizaion including oal choleserol mobilizaion during exericse, i was expeced ha he free choleserol level would increase as well. Since he percen free choleserol level increased significanly, i was indirec evidence ha he enzyme LCAT was unable o eserify he free choleserol a he same rae ha he free choleserol was mobilized. A sudy by Abdulla e al, (1969) has noed ha free choleserol is mobilized faser han sauraed or mono-unsauraed choleserol esers which suppors he resuls of his sudy. Several sudies have indicaed ha he LCAT eserifying aciviy decreases wih age (Gherondache, 1963; Wagner & Poindexer, 1952). Thus a greaer raio of eserified choleserol has been found in younger persons han older individuals (Gherondache, 1963; Lopez e al, 1967; Wagner & Poindexer, 1952). In he presen sudy, here was no significan difference in percen free choleserol beween he young and old groups. Since he groups were mached for weigh and physical finess, i is possible his may accoun for conflic wih he lieraure. In summary, he daa in his sudy sugges he following: (1) Shor-erm physical exercise increased he oal choleserol and boh he absolue and percen free choleserol from he resing sae o he submaximal exercise sae, o he maximal exercise sae, and decreased in he recovery period. (2) There was no significan change in free serum choleserol level due o a four-monh physical finess programme which did no aler he body weigh. (3) The high-fi group had a significanly lower free choleserol level han he low-fi group bu had similar percen free choleserol values. (4) There was no significan difference beween age groups mached for physical finess and weigh for he serum oal choleserol, free choleserol or percen free choleserol levels.

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