Ultra x mex­ico 2019: PREPARING FOR THE ALTITUDE

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 metres 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 10 km 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
Pre TestPost TestDif­fer­ence
Heart rate — aver­age dif­fer­ence between sea level and alti­tude7 bpm1 bpm-5 bpm
Heart rate — max­im­um dif­fer­ence between sea level and alti­tude12 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 in to day 1, 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 6 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.