Cof­fee and work­outs

Sunday Tribune - - WELLNESS -

are con­sid­ered to be mod­er­ate metabolis­ers, whereas peo­ple with two copies of the slowmetabolis­ing vari­ant are, of course, slow caf­feine metabolis­ers.

About 40% of us are thought to be mod­er­ate metabolis­ers, with the re­main­ing 10% be­ing ge­net­i­cally slow metabolis­ers.

In 2016, el-so­hemy and his col­leagues pub­lished a study in JAMA show­ing that slow metabolis­ers had a height­ened risk of heart at­tacks if they fre­quently drank cof­fee, com­pared to peo­ple who were ge­net­i­cally clas­si­fied as fast caf­feine metabolis­ers. The sci­en­tists the­o­rised that the drug, which can con­strict blood ves­sels, hung around and pro­duced longer-last­ing – and in this case un­de­sir­able – car­diac ef­fects among the slow metabolis­ers.

But few large ex­per­i­ments had fo­cused on how peo­ple’s CYP1A2 ge­netic pro­file might in­flu­ence their ath­letic per­for­mance after swal­low­ing caf­feine.

So for the new study, which was pub­lished this month in Medicine & Sci­ence in Sports & Ex­er­cise, el-so­hemy, to­gether with his grad­u­ate stu­dent Nanci Guest and other col­leagues, de­cided to ply about 100 will­ing, young, male ath­letes with var­i­ous doses of the drug.

The sci­en­tists swabbed the men’s cheeks, an­a­lysed their CYP1A2 genes and, based on which vari­ants each man car­ried, cat­e­gorised them as fast, mod­er­ate or slow caf­feine metabolis­ers.

Then they had the ath­letes com­plete three separate ses­sions of ped­alling a sta­tion­ary bi­cy­cle for 10 kilo­me­tres as quickly as pos­si­ble. Be­fore one ride, the men re­ceived a low dose of caf­feine (2 mil­ligrams for ev­ery kilo­gram of their body weight, or about the amount found in one large cup of cof­fee). Be­fore an­other, they swal­lowed twice as much caf­feine; and be­fore a third, a placebo.

Their sub­se­quent time trial re­sults showed that, on ag­gre­gate, the men per­formed bet­ter with caf­feine, es­pe­cially after the higher amount.

But there were sub­stan­tial dif­fer­ences by gene type.

The fast metabolis­ers rode nearly 7% faster after they had downed the larger dose of caf­feine com­pared to the placebo. The mod­er­ate metabolis­ers, by con­trast, per­formed al­most ex­actly the same whether they had re­ceived caf­feine or a placebo.

It was the slow metabolis­ers, how­ever, who showed the great­est im­pact, al­though in a neg­a­tive di­rec­tion. They com­pleted the 10 kilo­me­tre ride about 14% more slowly after the higher dose of caf­feine than after the placebo.

Just how caf­feine dif­fer­en­tially boosted or blunted the men’s ath­letic per­for­mance re­mains un­clear.

But el-so­hemy sus­pects that, as in the heart-at­tack study, caf­feine lin­gered in the slow metabolis­ers, nar­row­ing their blood ves­sels and re­duc­ing the flow of blood and oxy­gen to tir­ing mus­cles.

In fast metabolis­ers, the drug likely pro­vided a quick gush of en­ergy and then was cleared from their bod­ies “be­fore it could do the bad stuff”, he says.

This study in­volved only healthy young men and bi­cy­cling. It can­not tell us whether caf­feine like­wise gooses or in­hibits per­for­mance for other peo­ple in other sports.

And it can­not an­swer the broader ques­tion of whether we need a ge­netic test be­fore de­cid­ing if we should main­line cof­fee in ad­vance of our next work­out.

Phys­i­cal per­for­mance in­volves, after all, so many fac­tors, in­clud­ing mo­ti­va­tion, sleep, stress, over­all nu­tri­tion, and the work­ing of a vast num­ber of genes, many still be uniden­ti­fied.

So if you find that cof­fee seems to im­pede your per­for­mance, you could use a ge­netic test to char­ac­terise your CYP1A2 gene and con­firm that you are a slow metaboliser. Or you could not drink cof­fee be­fore you ex­er­cise. – The New York Times

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