Lac­tic Test­ing and Field Test­ing for Cy­cling

Triathlon Magazine Canada - - Training Bike - by Dan Smith

Fromwheel hub to crank arm to ped­als, cy­cling power me­ters have be­come in­creas­ingly so­phis­ti­cated and pop­u­lar. In fact, there was a 14 per cent in­crease in the use of power mea­sure­ment de­vices at the 2013 Iron­man World Cham­pi­onships (from 20 per cent in 2012 to 34 per cent). Fur­ther­more, many pros made their race data avail­able to view­ers online within min­utes of fin­ish­ing the bike leg.

Mea­sured in watts, power is the ab­so­lute value put to the ped­als. It al­lows the ath­lete and coach to pre­cisely mea­sure the work that is be­ing done: 200 watts is 200 watts. Be­cause of this the ath­lete can be sure of go­ing easy on re­cov­ery days and hard enough dur­ing in­ter­vals. While heart rate is of­ten used to de­ter­mine ef­fort or pace, it’s sub­ject to the ef­fects of fa­tigue, tem­per­a­ture, al­ti­tude or diet. Power al­lows ath­letes to quan­tify when they are feel­ing strong or tired; on a good day he or she may re­quire 60 per cent max­i­mum heart rate to achieve a wattage that on another day may re­quire 65 per cent max­i­mum heart rate.

In or­der to use a power me­ter ef­fec­tively, one has to de­ter­mine the ap­pro­pri­ate power ranges that stress the var­i­ous en­ergy sys­tems the hu­man body is able to call upon. There a num­ber of dif­fer­ent schools of thought re­gard­ing how to de­fine and dif­fer­en­ti­ate th­ese en­ergy sys­tems based upon phys­i­o­log­i­cal cost and the time the ath­lete is able to work in each zone. The most com­mon sys­tem used by coaches and ath­letes to­day is lac­tate thresh­old rather than max­i­mum heart rate.

Con­trary to pop­u­lar be­lief, lac­tate is not an evil, burn­ing so­lu­tion that cour­ses through your veins when you work hard. It’s a nat­u­ral by-prod­uct of the mus­cles burn­ing glu­cose and pyru­vate in the pres­ence of oxy­gen to form atp, the en­ergy used to con­tract the mus­cle. Lac­tate is re­turned to the liver to be re­pro­cessed and turned back into glu­cose. When the blood stream, liver and/ or glyco­gen lev­els in the body are un­able to keep up with this process, we reach our aer­o­bic thresh­old (mus­cles are us­ing the oxy­gen in the blood to help with atp cre­ation). This is typ­i­cally what we call lac­tate thresh­old, above which, the mus­cles are no longer able to get enough oxy­gen and the sys­tem goes anaer­o­bic which can only be main­tained for a short time.

With lac­tate blood test­ing me­ters, one can de­ter­mine a fairly ac­cu­rate point where the ef­fort goes from aer­o­bic to anaer­o­bic. Lac­tate lev­els are mea­sured in mil­limols per litre (mmol/ L) and the cur­rent process bases thresh­old when the lac­tate con­tent reaches four mmol/ L or there is an abrupt change in lac­tate val­ues. Keep in mind this point is not an on/off switch, it hap­pens over a rel­a­tively nar­row heart rate range. This ef­fort also co­in­cides with the max­i­mum ef­fort one can main­tain for 45 min­utes to an hour and, when us­ing power, is known as func­tional thresh­old power or ftp. An in­di­vid­ual’s power zones are then de­rived from this value.

The two ways to de­ter­mine thresh­old power are ei­ther step test (a grad­ual in­crease in load), or a short time trial. Dur­ing a step test, the ath­lete rides on a trainer that has con­trol­lable power re­sis­tance, like a Com­pu­Trainer. Af­ter a warm-up of 15 to 20 min­utes, the test starts off with a low load and the re­sis­tance is in­creased by a set amount (usu­ally 20 watts for women and 30 watts for men) ev­ery three min­utes. A blood sam­ple is taken at the end of each in­ter­val and an­a­lyzed in a tester. The test is con­tin­ued un­til the ath­lete can­not hold a pre­de­ter­mined ca­dence. Time, power and blood lac­tate lev­els are plot­ted on a graph and the cor­re­spond­ing val­ues where the line def lects at 4 mmol/ L is con­sid­ered lac­tate thresh­old and thresh­old power.

The field test can be con­ducted on a sta­tion­ary trainer or out­side on a f lat road. Care should be taken to make sure con­di­tions are the same

from test to test. If out­doors, there are en­vi­ron­men­tal fac­tors to be aware of; avoid wind, hills or stop signs. En­sure that the test falls in the ath­lete’s work­out cy­cle at the same time. For ex­am­ple, ath­letes should aim to make the three days lead­ing up to the test as easy – al­low­ing ath­letes to be fresh.

As with any test ef­fort, be­gin by warm­ing up eas­ily for 20 min­utes then do a se­ries of four, one-minute build in­ter­vals with two min­utes re­cov­ery af­ter each. Then do a five-minute time trial ef­fort fol­lowed by 10 min­utes easy. Now you are ready to go for the best av­er­age ef­fort for 20 min­utes, a max­i­mal steady state ef­fort that is un­com­fort­able, but man­age­able; any­thing above it is un­sus­tain­able and re­sults in an abrupt drop off, avoid sprint­ing to the fin­ish. To de­ter­mine ftp take the av­er­age power for the test and sub­tract five per cent from this value. This is not quite as sci­en­tific as blood val­ues, but with reg­u­lar tests it is ac­cu­rate. It is im­por­tant to re­peat ei­ther of th­ese tests at reg­u­lar in­ter­vals to stay up to date with im­prove­ments as the rider gets stronger.

Us­ing Power Zones to Im­prove Per­for­mance

Ev­ery ath­lete is dif­fer­ent, there is no one pre­scrip­tion to im­prov­ing per­for­mance. For newer ath­letes com­ing from a seden­tary back­ground, of­ten­times just get­ting out and rid­ing is go­ing to im­pact fit­ness the most. Grad­u­ally in­creas­ing mileage over a num­ber of months in the re­cov­ery and en­durance zones will im­prove car­dio­vas­cu­lar fit­ness with­out overly stress­ing the heart. By stay­ing be­low Zone 2 ( 75 per cent of ftp), the typ­i­cal age group Iron­man power out­put, ath­letes will im­prove bike stamina and be able to ride longer at a given heart rate.

Get­ting faster or in­creas­ing power is another mat­ter for a sea­soned racer. Stud­ies have shown that re­peated work at or close to ftp pro­vide the high­est fit­ness ben­e­fits. How­ever, max­i­mal ef­forts for ev­ery work­out are not phys­i­o­log­i­cally pos­si­ble. One needs to bal­ance re­cov­ery, strength and speed, mus­cu­lar and car­dio­vas­cu­lar over the week. There are a num­ber of work­outs that take ad­van­tage of the power me­ter. Strength set: An ef­fort be­tween three and twenty min­utes with a ca­dence of 60 rpm at 85 to 90 per cent ftp at low heart rate, fol­lowed by 50 per cent time of in­ter­val easy spin ( less than 55 per cent ftp) ( Zone 1) be­tween in­ter­vals. One mis­take with us­ing a power me­ter is to al­ways strive for the high­est achiev­able num­ber. The goal for this par­tic­u­lar work­out is to stress the mus­cu­lar sys­tem by ap­ply­ing a lot of pres­sure on the ped­als. Thresh­old set: Short ef­forts of three to eight min­utes with a ca­dence of 90 to 95 rpm at 105 per cent ftp ( Zone 4 to 5), fol­lowed by an equal time of re­cov­ery spin ( Zone 1) be­tween ef­forts. This in­ter­val im­proves lac­tate thresh­old and car­dio­vas­cu­lar fit­ness as one is work­ing right at that up­per limit. When per­form­ing this work­out based on power, heart rate grad­u­ally rises such that the first in­ter­val will seem eas­ier than the rest. By the last in­ter­val, the heart will be work­ing at max­i­mum ca­pac­ity as a re­sult of car­ry­ing the load from the ear­lier in­ter­vals. Thresh­old En­durance set (train­ing for half dis­tance races): three hour ride with in­ter­vals of 90 to 95 per cent ftp ( low to high Zone 4) (20 min­utes Zone 1 re­cov­ery in be­tween). This is a way to in­clude higher than race ef­fort in a longer work­out. Of course th­ese are only the bike work­outs for a triathlon train­ing pro­gram, swims and runs need to be ac­com­mo­dated. Be sure to in­clude a run off the bike at reg­u­lar in­ter­vals. Fol­low­ing a pre­scribed plan us­ing a power me­ter al­lows one to pre­cisely dial in their ef­forts and know ex­actly where im­prove­ments are be­ing made. LifeS­port se­nior coach Dan Smith has been in­volved with mul­ti­sport for more than 15 years. Visit LifeS­portCoach­

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