Unbound Gravel 200

Unbound 200 in Emporia, Kansas, is one of the most demanding gravel races on the endurance calendar. Its 200-mile course pushes athletes to their limits, combining rough terrain, intense competition, and often extreme heat. In preparation for the 2025 edition of the race, Alex worked closely with the PF&H sports science team to develop a performance strategy that addressed three key challenges: fueling for sustained energy, maintaining his hydration status under heat stress, and adapting physiologically to the expected stressful environmental conditions.

Alex’s fueling strategy was carefully designed to reflect the physiological demands of ultra-endurance racing, where maintaining a high and consistent carbohydrate intake is critical for performance. In the opening phase of the race (start to the first aid station at mile 70), Alex consumed carbohydrates at a rate of ~115g/h. This aggressive fueling approach was essential given the tough start to the race, during which he averaged 295W and reached an average speed of ~40.2 km/h (~24.9mph) over the first two hours. The intensity resembled a short criterium rather than the opening of a ten-hour gravel event, making early carbohydrate availability essential for glycogen preservation and sustained power output. This period included several mental and physical challenges. After an early crash (at ~40 mile point), Alex entered what he described as “survival mode” and had to work himself back into a racing mindset, which was encouraged by his race history and galvanised by finding a small group to ride and work with.

At the first aid station, he re-stocked with one PF 60 Chew Bar, three PF 90 gels, and one PF 30 Caffeine gel and transitioned into the middle section of the race (mile 70 to mile 148). Initially, he found himself working well in a small group, with everyone taking their turn at the front; the group rode at a good tempo and applied power sensibly during the climbs. During this period however, Alex’s carbohydrate intake dropped to ~82g/h. The reduced fueling rate observed during this section is not uncommon in long-distance events; athletes often experience dips in appetite, gastrointestinal comfort, or simply lose focus on intake. On this occasion though, the lower rate of carb intake was due to the middle sector of the race taking longer than planned, and it got to a point where Alex had consumed all of his fuel but still had ~10 miles to reach the second aid station. It's not unsurprising that Alex described the second half of the middle sector as a “roller coaster, both physically and mentally.”

Following a re-stock of gels and another chew bar at the second aid station (at mile 148), Alex made a concerted effort to increase his intake again. During this final stretch, he consumed carbohydrates at a rate of ~122g/h. This surge in fueling included a large bolus of carbohydrate, comprising a PF 90 Gel, a PF 60 Chew Bar, and a PF 30 Caffeine Gel, all taken within a 20-minute window. The timing and quantity of this intake were deliberate, aiming to restore energy availability and cognitive alertness during the most fatiguing part of the race. This approach is well supported by research demonstrating that high carbohydrate availability in the later stages of prolonged endurance exercise can reduce perceived exertion, sustain power output, and delay fatigue.

Preparing for the heat

Anticipating high temperatures in Emporia, Alex dedicated a significant portion of his training to heat acclimation. His preparation began with an initial session in the Precision Performance Lab in February, where baseline measurements of sweat rate and heat tolerance were established. These data points informed the structure of a heat acclimation programme that combined both active and passive strategies over several months ahead of the big race.

Active heat training sessions were integrated into his weekly routine and included indoor rides conducted without a fan and with additional clothing to elevate core temperature and increase sweat rate. In parallel, Alex also incorporated post-exercise sauna exposure (following sessions at ambient temperature) to extend the period of thermal stress and promote further adaptation. This dual approach aimed to improve his thermoregulatory responses and cardiovascular efficiency in hot conditions; this strategy has been shown to be effective in triathletes.

In late May, Alex returned to the Precision Performance Lab for a second block of five heat sessions. This served both as a final heat stress stimulus and a re-evaluation of his physiological adaptations. Between February and May, his power output during a standardised one-hour heat session increased by 13% while maintaining the same heart rate, indicating improved cardiovascular efficiency. More notably, his normalised watts per beat per minute - a proxy for the relationship between internal strain and external output - improved by 21%. This metric demonstrated a more efficient cardiovascular response to thermal stress. His sweat rate also increased by approximately 30% (from ~1.9L/h to ~2.6L/h), reflecting an earlier onset of sweating and greater overall sweat output, both of which are markers of successful heat acclimation. These adaptations positioned Alex to better tolerate and perform in the hot, dry conditions expected on race day.

Hydration during the event

Alex’s hydration plan was built around two key data points: his individual sweat sodium concentration and predicted sweat rate under race conditions. The results of his sweat test characterised him as a ‘moderately-salty’ sweater. Using this information, along with a newly developed sweat rate prediction model, his fluid and sodium replacement strategy was customized to minimise fluid losses and maintain electrolyte balance throughout the race. Overall, the aim was to prevent total body mass losses from exceeding 2%, a threshold beyond which endurance performance is known to deteriorate significantly.

From the start of the race, Alex carried a 3-litre hydration bladder dosed with correctly mixed PH 1500 (Tablets), as well as two 650ml bottles filled with plain water. At both major aid stations (mile 70 and mile 148), Alex replaced his bladder with a fresh, iced version of the same mixture he started with, and took on two additional water bottles containing plain water. The use of chilled fluids served a dual purpose: it supported hydration and also provided a cooling effect, particularly helpful given his race suit was equipped with a specific compartment to house the bladder, which rested almost on the skin.

He consumed fluids at an average rate of just under ~1L/h during the first three-quarters of the race, demonstrating good discipline and awareness of the risks of becoming dehydrated on performance. During the final portion of the race, Alex increased his fluid intake to ~1.3L/h. This upturn aligned with rising temperatures and accumulated fatigue.

Caffeine was used selectively throughout the race to support mental focus, perception of effort, and overall drive, especially during high-stress or high-fatigue phases. Alex began the race with a PF 30 Caffeine Gel, aiming to support alertness and focus during what turned out to be a chaotic, high-intensity opening.

Alex consumed a second caffeine gel shortly after the first aid station, timed to maintain central nervous system stimulation and help manage the psychological toll of the race’s middle section. The final dose was taken after the second aid station, again in the form of a caffeine gel, as Alex prepared himself for the closing 50 miles of riding.

Over the course of the event, Alex’s caffeine intake fell well within the recommended ergogenic range and is supported by a substantial body of evidence demonstrating caffeine’s ability to enhance endurance performance, reduce perceived exertion, and improve cognitive performance during prolonged exercise.