All Out, Every Day

By Week Three, Team Nautilus had been rowing continuously for their first full week in open water following departure from Tower Bridge. The data from this period is the most demanding we have recorded so far - and it reveals just how extreme the physiological cost of this challenge has become.

This is Week Three.

A Note on This Week's Data

Sleep and recovery metrics - including recovery score, HRV and resting heart rate - were unavailable during this reporting period due to limitations in data collection while at sea. This week's report therefore focuses on workload, strain and energy expenditure.

The strain data alone tells a remarkable story.

Week Three Key Findings (June 16th – June 22nd)

Strain

Average daily strain across the crew reached 18.7 - a 41.7% increase on Week Two - placing the entire crew in the WHOOP "All Out" strain category (18–21). This is the highest band on the scale, reserved for the most extreme physiological efforts.

Strain values frequently reached 20–21 - the upper limit of the scale. To put that in context, a single hard training session for an elite athlete might produce a strain score of 15–17. The Nautilus crew are sustaining scores above 18 as a daily average, across every member of the team, day after day.

Energy Expenditure

Average calories burned rose to 3,020 kcal per day - up 30.7% from Week Two. Individual expenditure ranged from 2,309 to 4,426 kcal per day, highlighting the significant variation in workload between crew members depending on body mass, rowing mechanics and shift patterns.

One crew member burning 4,426 kcal per day is consuming the energy equivalent of running approximately two marathons - every single day.

Workout Volume

Average recorded workouts reached 32.7 per week - a 98.2% increase on the previous week. That is close to five workouts per day, every day, produced by the relentless accumulation of two-hour rowing blocks within the rota structure.

Individual Highlights

• Highest strain: 20.4 daily average - up 64.5% - with 4,426 kcal/day energy expenditure, the highest in the crew.
• Highest workout frequency: 46 recorded sessions across the week - an average of 6.6 per day - with a comparatively moderate 2,309 kcal/day, suggesting a workload built around consistency and frequent shorter efforts.
• Largest strain increase: One crew member increased from a daily strain of around 12 to 20.2 - a 66.9% rise - operating consistently within the All Out range throughout the week.

What the Data Tells Us

Week Three represents a clear shift into sustained extreme endurance. The crew are no longer adapting to the expedition - they are operating within it at full load, and the data reflects that.

At strain levels consistently above 18, recovery capacity, sleep quality, hydration and fuelling become the primary performance levers. With sleep and recovery metrics unavailable this week, our team cannot assess how well those systems are holding up - but the magnitude of strain makes managing the inputs precisely more important than ever.

The variation in calorie expenditure across the crew - nearly 2,000 kcal per day between the lowest and highest individual - is a reminder that this is not a uniform physiological experience. Each crew member's body is responding differently to the same conditions, and individual nutritional and recovery strategies must reflect that.

Week Three Focus: Managing High Strain Load

• Strain is in the All Out category across the whole crew. Recovery during off-shift periods is not optional - it is the foundation that keeps performance possible in the next shift.
• Energy intake must match energy output. With crew members burning between 2,300 and 4,400 kcal per day, fuelling gaps will accumulate rapidly into fatigue and injury risk.
• Hydration and electrolyte replacement must be consistent across all conditions, regardless of temperature or perceived thirst.
• Every rest window is a recovery window. Sleep, nutrition and stillness - in that priority order - during every off-shift period.

Follow the PEAK4 x Team Nautilus performance tracker for weekly updates throughout the GB Row Challenge 2026. The crew continue their circumnavigation of Great Britain - rowing, resting and rowing again, one two-hour block at a time.