Pre­par­ing To Race At Alti­tude: Ultra X Mex­ico 2019

Writ­ten By Mar­ina Ranger

Mar­ina Ranger is a GB Age Group Triath­lete, ultra run­ner, and all-round endur­ance chal­lenge enthu­si­ast. In 2016, she ran 500km in 5 days to raise money for the Pink Rib­bon Found­a­tion. Mar­ina has also com­pleted sev­er­al Ultra X events, includ­ing win­ning the inaug­ur­al Ultra X Mex­ico in 2019.

2 Decem­ber 2019

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Read­ing Time: 7 minutes

Mar­ina Ranger (First female fin­ish­er at Ultra X Mex­ico 2019) writes about her exper­i­ence at The Alti­tude Centre in pre­par­ing for the race.

I knew when sign­ing up for Ultra X Mex­ico it would be the toughest multi-stage ultra I have done to date. Mex­ico was my sixth; and I knew my next one had to be a step up from the rest, some­thing that would ser­i­ously chal­lenge me and force me to break new bound­ar­ies.

Much of Mex­ico was unknown ter­rit­ory for me, namely the alti­tude and elev­a­tion. The race star­ted at 2,300m above sea level and over the course of 250km, we had to climb 12,000m. While I have exper­i­ence in single stage moun­tain ultras, Mex­ico is doing this every day, for five con­sec­ut­ive days, which is some­thing I have nev­er put my body through. Giv­en this, I knew I had to adapt my train­ing to focus on the con­di­tions I had the least exper­i­ence and con­fid­ence in, appre­ci­at­ing these would be the vari­ables that would be the largest factor in affect­ing my run­ning abil­ity.

Rep­lic­at­ing the con­di­tions of a race is an approach I take in train­ing for any race. Liv­ing in Lon­don provides bar­ri­ers to both train­ing with elev­a­tion and alti­tude as it is at sea level and pan­cake flat. How­ever, we are lucky enough in this day and age to have everything at the tip of our fin­gers, includ­ing an alti­tude cham­ber where people train to exper­i­ence a harder workout as they are essen­tially starved of oxy­gen.

This cham­ber is in the Alti­tude Centre by Bank tube sta­tion and is a huge factor behind why I had the race of a life­time fin­ish­ing as first lady in Ultra X Mexico’s first edi­tion of the race. The Alti­tude Centre is a train­ing room/chamber that has reduced oxy­gen levels to rep­lic­ate an alti­tude of 2,700m above sea level with tread­mills, bikes, mats and a couple of row­ing machines.

At sea level, oxy­gen con­tent is 20.9% and at 2,700m above sea level this reduces to 15% oxy­gen. At alti­tude, giv­en the lower oxy­gen levels, your body has to work harder to deliv­er oxy­gen to the muscles, because there is less of it. Your body’s abil­ity to deliv­er oxy­gen to the muscles at alti­tude can be meas­ured through your blood oxy­gen sat­ur­a­tion levels (spO2). spO2 can be con­sidered as the per­cent­age of your red blood cells that are sat­ur­ated with oxy­gen. As you exer­cise, spO2 gen­er­ally falls as you begin to util­ise more oxy­gen and even more so when at alti­tude.

Before I star­ted train­ing at the Alti­tude Centre, I had an alti­tude test to be used for a com­par­is­on against the same test at the end of the pro­gramme. The test con­sisted of base line health checks includ­ing; rest­ing heart rate, blood pres­sure, breath­ing reflex and lung func­tion fol­lowed by a tread­mill set (below) at sea level and then at 2,700m above sea level. Dur­ing the tread­mill set they meas­ure your heart rate and spO2 levels at each inter­val and com­pare the two to see how your body reacts to being at alti­tude.

Tread­mill ramp test set:
2 mins @ 1% incline
2 mins @ 2% incline
2 mins @ 3% incline
2 mins @ 4% incline
2 mins @ 5% incline
2 mins @ 6% incline
Total time: 12 mins
Speed for both tests: 10.5km/hr (this can increase/decrease depend­ing on indi­vidu­al abil­ity)

My res­ults indic­ated I was aver­age at adapt­ing to the lower oxy­gen levels. My spO2 levels decreased by 14%! Addi­tion­ally, my heart rate was on aver­age 7 beats faster per minute at alti­tude, with the largest dif­fer­ence being 12 beats per minute faster. Based on these find­ings, I knew the inter­mit­tent hyp­ox­ic expos­ure of train­ing at alti­tude would help align my physiology with what it was at sea level and hence improve my per­form­ance in Mex­ico.

I signed up to their 6-week pro­gramme, which includes 15 ses­sions and 5 pod ses­sions (I will explain what these are later). This worked out at 2 ses­sions per week up until the last few weeks before the race where I increased this to 3 in addi­tion to the 5 pod ses­sions.

They hold classes so the major­ity of my ses­sions were spin or run classes inside the cham­ber, which was great for motiv­a­tion. The classes have been designed by the sports sci­ent­ists at the centre and are a vari­ety of high intens­ity sets to improve VO2 Max. They’ve got watt bikes, which is a huge win­ner for me. I can’t stand spin classes without meters and hence any gauge of how far you’ve gone or how your power com­pares to your last ses­sion! The read­ings get uploaded to their online portal at the end of each ses­sion so you can really see how you’re per­form­ing and improv­ing week on week.

Each class I did was dif­fer­ent so it nev­er became com­fort­able and always pushed me enough to feel super sat­is­fied at the end of each class. Plus, the instruct­ors are really fant­ast­ic; great energy, so friendly and push you the per­fect amount to keep break­ing those bar­ri­ers. In addi­tion to the classes, I did a few self-made ses­sions on the tread­mill at incline. These tread­mills go up to 20% incline!! Couldn’t have been more per­fect for my hill train­ing!

The pod ses­sions require no exer­cise as you simply sit down for an hour with a mask on and off your face in 5-minute inter­vals for one hour. This tech­nique is called Inter­mit­tent Hyp­ox­ic Expos­ure where you breathe in short bursts of moun­tain air, altern­ated with nor­mal air to help you adapt to low oxy­gen levels even quick­er. Each sub­sequent ses­sion is at a high­er alti­tude than the last. My first ses­sion star­ted at 3,500m and by the fifth I was at 5,438m. They go up to over 8,000m but there was no need for me to go much fur­ther as the race was only at 2,500m.

Through­out the six weeks I felt I was get­ting notice­ably fit­ter as my pace was drop­ping for the same rate of per­ceived exer­tion. For example, on a steady 10km run, my pace was 30 seconds faster per km. I’ve genu­inely nev­er had such quick and sig­ni­fic­ant improve­ments in my run­ning speed in all my sev­en years of run­ning. At the end of my pro­gramme, the week before I flew to Mex­ico, I repeated the same health tests and tread­mill ramp test that I did before I star­ted train­ing at the Alti­tude Centre. Not only did it feel bet­ter but my res­ults sig­ni­fic­antly improved!

Most impress­ively, my heart rate only increased by 1 beat per minute on aver­age through­out the whole test. That indic­ated that I would be bet­ter at deal­ing with the added phys­ic­al demands of alti­tude in Mex­ico. A lower heart rate also improves effi­ciency, mean­ing I could sus­tain my energy for longer. My blood oxy­gen sat­ur­a­tion (spO2) levels also improved, indic­at­ing my body had more oxy­gen to work with at alti­tude and was there­fore bet­ter at get­ting oxy­gen to the blood at alti­tude. The below table explains the dif­fer­ence in my tread­mill ramp test res­ults between the ini­tial test at the start of my 6 week pro­gramme and the test just before I left for Mex­ico.

Pre / Post Test Res­ults Com­par­is­on
Vari­ablePre-TestPost-TestDif­fer­ence
Heart rate (aver­age dif­fer­ence between sea level and alti­tude)7 bpm1 bpm-5 bpm
Heart rate (max­im­um dif­fer­ence between sea level and alti­tude)12 bpm3 bpm-9 bpm
Blood oxy­gen sat­ur­a­tion (aver­age dif­fer­ence between sea level and alti­tude)-14%-10%4%
Blood oxy­gen sat­ur­a­tion (max­im­um dif­fer­ence between sea level and alti­tude)-15%-10%5%

While I am a suck­er for hard data, bey­ond fig­ures, I value ‘feel’ just as import­antly, so des­pite the pos­it­ive res­ults, I hate to get com­pla­cent and always leave an ele­ment of doubt in the back of my mind as a buf­fer in case on race day I don’t feel on good form. Luck­ily, I didn’t end up need­ing this buf­fer as I felt really strong and able to per­form at a high stand­ard against my ini­tial expect­a­tions and also the rest of the field.

I felt fully con­fid­ent in my abil­ity to get through the race and in good time soon into day one, so I knew early on I would be in for a good week of racing. This con­fid­ence boost enabled me to enjoy the exper­i­ence even more because even without hav­ing reached the fin­ish line, I felt a sense of self-sat­is­fac­tion in know­ing I had pre­pared well in my train­ing.

And it was just as well I felt this good because it was relent­lessly bru­tal. Every day brought a new chal­lenge, wheth­er that be the tech­nic­al trails, heat, end­less climb­ing, loose rock, thin air or steep and dan­ger­ous des­cents. It is the first multi stage race out of the six I’ve done where I’ve stood on the start line each day in pain from the day before. It’s also the most var­ied race I have done, with almost all of the vary­ing factors bring­ing their own ele­ment of a per­son­al battle to the exper­i­ence.

It’s a beast of a race and in my opin­ion needs sub­stan­tial pre­par­a­tion for. Obvi­ously, the res­ult of a race can’t be put down to one ele­ment, it is a com­bin­a­tion of many. How­ever, as I men­tioned at the begin­ning, I truly believe that hav­ing this expos­ure to train­ing at alti­tude was a major reas­on why I had such a good race and hence an even more incred­ible exper­i­ence run­ning in Ultra X Mex­ico.  

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