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altitude Tent Training Diary

The following blogpost is a consolidation of diary entries from an elite male cyclist. He used the Affinity Altitude sleeping system to acclimatise and maximise training prior to an endurance cycling race at altitude (one of the most important Italian Gran Fondo cycling events of the year).

Athlete stats prior to using the tent:

Sex: Male

Age: 36

Sport: Cycling

Height: 182cm

Weight: 67.3kg

Haemoglobin: 154g/dL

Haematocrit: 43%

Day 1

9h30m in tent (1683m altitude).

Was agitated the first 3 hrs or so in the tent, then slept well. Noise levels acceptable, however intermittent airflow slight distraction to sleep.

AM: 30’ easy running, definitely noticed a change in the breathing pattern (needed a deep breath every now and then). Low-ish energy levels. Midday: 1h bike w/ 3×10′ at 2709m simulated altitude. Felt drained and called it a day half way through the session as this was not 100%. Recovery felt much slower.

PM: Cryotherapy session.

Day 2

10h in tent (1900m altitude).

Slept with ear plugs on – much better, effectively silent. It appears I am eliminating more liquids; going to the bathroom during the night, normally do not have to do this. Started taking iron supplements.

AM: 30′ very easy running.

Overall rest day today ahead of the big weekend.

Day 3

9h in tent (2300m altitude).

Slept better even better still, however do feel that energy levels have been low in the day.

AM: Tough 3h bike session, with 70 minutes tempo. Very strong uphill, less so on the flat.

Day 4

9h in tent (2300m altitude).

Slept well and it is the first day where I felt full energy again.

AM: 4h25’ ride. Felt strong the whole session despite the rain.

Day 5

9h in tent (2300m altitude).

AM: No session.

PM: Cryotherapy and easy 30′ run.

Day 6

8h 30m in tent (2400m altitude).

Slept ok, a bit too warm.

AM: 30′ easy running. Mid: 1h bike session at 2710m simulated altitude, including 3×10 minutes tempo. Felt good even though HR did not reflect this. Certainly better than last time (see Day 1), but not as good as “pre-tent” (very close, though).

PM: 30′ easy run.

Day 7

9h 30m in tent (2400m altitude).

Sleep was ok, even though I seem to have woken up every 3 hrs.

AM: 30′ easy running (short of breath/same feeling after sleeping 1st night in the tent).

Day 8

9h 30m in tent (2400m altitude).

Probably the best night I had in terms of sleep quality, no waking during the night.

AM: Did not run as I felt a weird pain in my right calf. 3×10 minutes tempo on the bike.

PM: 30′ easy run.

Day 9

9h in tent (2400m altitude).

Slept well (some cramps in right calf).

AM: 35′ easy running, no calf issues whatsoever. Easy day ahead of the weekend.

Day 10

9h in tent (2700m altitude).

AM: 3h on the bike including 70mins tempo. Dropped everyone and felt stronger than ever! Here we go! Ice bath and massage to recover.

Day 11

9h 30m in tent (2700m altitude).

AM: 3h30min hard ride on the flat. Felt even stronger than yesterday! Not too tired in the afternoon as well.

Day 12

9h 30m in tent (2700m altitude).

Slept really well with air conditioning on.

AM: 30min easy run. 1h session on the bike including 3×10 minutes in simulated altitude of 2709m. Crazy how well it went, with max HR only 155, 158, 161 for each 10 minutes respectively. This session was almost to good to believe, I had to keep checking that the altitude setting was as high as it was!

PM: 20′ easy run.

Day 13

9h 30m in tent (2700m altitude).

Slept really well with AC on – a trick worth remembering for next time.

AM: 30min easy run. 1h session on the bike, including 3×10 minutes tempo. Went crazy well with only 155, 158, 161 max HR at 2709m altitude. This session was so good I couldn’t believe the altitude had been set correctly!

PM: 20 minute easy run.

Day 14

9h30m in tent (2700m altitude).

Weight 64.4 Kg (lightest I’ve ever been).

AM: 30′ easy run.

Day 15

10h in tent (2700m altitude).

PM: Last session at 2700m simulated altitude, 3x10min feeling fantastic. Lower HR ever recorded. Not losing power, but dropping weight and dropping HR! Fantastic feeling, hard work coming together.

Day 16

9h30m in tent (2700m altitude).

AM: 30min easy running. 

PM: 30min easy running.

Day 17

8h in tent (2700m altitude).

PM: Usual 3h on bike with 1h effort. Was flying, dropped everyone I normally never drop.

Day 18

9h30m in tent (2700m altitude).

PM: 30mins on the bike, then hill work flat out. Feeling great.

Day 19

9h30m in tent (2700m altitude).

AM: Rest.

PM: Last light gym session.

Day 20

9h30m in tent (2700m altitude).

AM: 30′ run easy.

PM: Rest.

Day 21

9h30m in tent (2700m altitude).

AM: 30′ easy running in the morning. 63.9kg, my new lowest ever adult weight! Felt like I was floating on the run!

Day 22

10h in tent (2700m altitude).

AM: Flight.

PM: Easy spin in the late afternoon for 50mins. Felling fatigued. HR higher than normal (both resting and exercising).

Day 23 (day 1 post tent)

2h30m on the bike in the mountains. Not feeling great, but is first ride so hopefully will settle into it.

Day 24 (day 2 post tent)

1h on the bike easy, feeling much better. Slept at 1600m on the mountainside, time to race tomorrow.

Day 25 (day 3 post tent)


Felt so strong on the climbs and absolutely incredible pulling away from the pack! A massive thank you to the team at Affinity Altitude for helping me towards this.

Athlete stats after using the tent:

Weight: 63.9kg

Haemoglobin: 174g/dL

Haematocrit: 52%

Peak power output improvement of 13 watts on a watt bike.


  • I slept in the tent for 21 consecutive days, totalling 205.5 hours cumulatively.
  • I started at 1600m and then gradually increased to 2700m by day 10 (continuing at this height until day 22). I would have ideally stayed in the tent for the recommended 4-6 weeks, however in this instance was limited to 3 weeks.
  • Sleep was initially more intermittent and definitely needed to drink more water before going to bed and overnight. Overall I believe sleep quality has not suffered too much (the noise of the generator is negated with ear plugs).
  • I was waking up in the morning with higher heart rate. Normally I am at 38-42 beats per minute (BPM), in the tent was at 55-60 BPM. Saturation levels were closely monitored with a saturation probe and SPO2 was kept at 90% most nights.
  • Both running and cycling performance was reduced in the first week, with peak power output down by 8-10 watts.
  • By day 10, my peak power output had broken even and I was back up to my baseline.
  • After day 10 I started to feel the real benefits. By day 21 I had increased my peak power output by 13 watts (an approximate 3% improvement in peak power output), in addition to having lost 3.4kg in weight (from 67.3kg to 63.9 kg) – significantly increasing my power to weight ratio. In other terms, this equalled the same benefits as 4 months of hard training had done in the past for me!