If you know CrossFit, you should probably know Sam Briggs.

She first qualified for the CrossFit Games in 2010 and, over a decade later, she is still absolutely crushing it.

She’s qualified for the games as an individual 9 times (with another as a team competitor), has had 4 Top 5 finishes at the Games including being crowned the 2013 Fittest Woman on Earth (the winner of the CrossFit Games). This performance was perhaps best exemplified by an astounding 1:27 half marathon…that took place on a rowing machine. That output earned her the apt nickname The Engine!

To maintain a place in the top tier of any sport for this length of time is an impressive feat.

But when the competition is undefined, constantly changing, and often intentionally completely out of left field – to truly test who is the fittest across all domains – and still maintain the top spots,  the term “impressive” seems like an understatement.

CrossFit lends itself to those looking to optimize their physiology and constantly improve in different domains. So it is no surprise that Sam chose to work with Supersapiens to ensure she was doing everything she could to help her continue to perform at the highest level possible.

With Supersapiens, Briggs has been methodically dialing in her nutrition during the Prime, Perform, and Recover periods of her day. She’s been working around her sleep and overnight glucose, improving her energy during her training sessions, and working hard to ensure she optimizes her glucose in her recovery window. She’s optimizing her intake during her training sessions – some of which are well over three hours long – to ensure she maintains intensity and quality in these sessions. This, in turn, has helped her manage her total caloric needs. Given how big a portion of her day is spent training, these needs become difficult to meet when only consuming fuel outside of training time. The key has been dialing in better fueling during training sessions, which aids her in optimizing her recovery, as well as dialing in her evening nutrition to improve her sleep.

To examine Sam’s workload is interesting, because it's both significant and extensive in nature. Training sessions at such length in duration, at such a high intensity with a somewhat intermittent nature are quite different to what most endurance athletes undertake in training.  The data has been so interesting to analyze.

Sam has just progressed through the semi-finals – off to the CrossFit Games yet again. It’s uncertain what awaits her at the games. But, for now, the data from the semi finals is enough for us to obsess over.

In these semi-finals, the athletes compete in 6 workouts across 3 days. This includes some classic CrossFit workouts like the Fran or the Murph. But it’s more likely we see a few out-of-left-field workouts, an extended medley workout, and a strength-based workout. As is clear from the semi-final data, the workouts range from less than 3 minutes to up to 25 minutes. The point is to get these done in the shortest amount of time possible. So, yes, intensity is extreme.

Stimulation of high blood glucose levels through activity requires the right mix of intensity and duration. Too short, and the body cannot increase glucose levels fast enough or does not need it to meet such a burst in energy demand. If the intensity is too low, there’s no demand for increased glucose delivery/utilisation above normal levels. It’s important to remember that glucose level can be driven by other factors beyond diet and exercise. Stress is one. And these are factors that even seasoned veterans like Briggs deal with.

Here are the details of Sam’s journey:

The Semis:

Day 1

Workout 1

3 rounds for time of:

21 thrusters

21 chest-to-bar pull-ups

Time cap: none

Result: 4th (4:47)

With only 5 minutes of total work, this one was straight up intensity. Five minutes of redlining, gritting your teeth, getting it done. You can see from the glucose graph in Figure 1 that Briggs knew she needed to be ready to go and had warmed up well, with a glucose of around 130-140 at the event start. You can see from Figure 1 that Sam had a good breakfast, avoiding rushes above 140 mg/dL and warmed up well, being metabolically ready to go when the event started. The carbohydrate content of this meal aids in filling glycogen stores after an overnight fast. The warm up is then crucial to ensure metabolic processes are working at the optimal rate possible before such an intense effort.

Workout 2

For time:

50 dumbbell shoulder-to-overheads

50 dumbbell deadlifts

50 GHD sit-ups

100 single-arm dumbbell overhead squats

50 GHD sit-ups

50 dumbbell deadlifts

50 dumbbell shoulder-to-overheads

Time cap: 25 min

Result: 10th (13:12)

Don’t be fooled by the time this one took: This is much more of an endurance workout than 13 minutes suggests. This is a good mix of intensity and duration to see some high glucose levels during the workout and after it.

After both of these workouts, you can see the glucose rushes associated with intake of some quicker carbohydrates to prompt recovery and get ready for the next workout. In an event like this, Recovery from the first event is preparation for the next. In the case of workout 1, it is Priming for workout 2.

Interestingly, we can easily spot a high-variability pattern between the 2 workouts of the day. As you can see the glucose level was fluctuating multiple times (180→110, 110→180→60, 60→120→60, 60→150→90) after workout #1 and before workout #2 highlighting strong metabolic perturbations that might have impacted hormonal control and therefore metabolism.

Whether a response to intensity or due to the feeding schedule, there might be room to improve here.

Figure 1: Sam’s Glucose Data from Day 1 of the CrossFit Games Semis

Day 2

Workout 3

For time:

30 muscle-ups

30-m dumbbell front-rack lunge

300 double-unders

20 muscle-ups

20-m dumbbell front-rack lunge

200 double-unders

10 muscle-ups

10-m dumbbell front-rack lunge

100 double-unders

Time cap: 25 min

Result: 2nd (16:25)

Similar in duration to workout 2, this one is very different. This is a mix of some more grinding and more super quick work. This is alternating in loads to create a nasty mix of prolonged output. This is probably the reason for the huge drop into hypoglycemia that Sam had after it, likely driven by a combination of high muscle uptake and a more inertial glucose output from the liver. But also some counter-regulatory mechanisms that the body put in place to handle such a rush during the workout.

Workout 4

Complete as many repetitions as possible in 10 minutes of:

10 snatches, 85lb.

Rest 1 min.

10 snatches, 125lb.

Rest 1 min.

10 snatches, 145lb.

Rest 1 min.

Max-rep snatches in time remaining, 165lb.

Time cap: 10 min.

Result: 25th (31 reps) Tiebreak: 5:37

The nature of the snatch movement, in its dynamism, imposes a unique metabolic demand on the body–even with sub-maximal weights. This is something unique to lifts like the snatch and clean. And it seems to be the genesis of the fairly significant glucose rise (as you can see in Figure 2) above what would be expected due to what seems like a lower level of stress given the pure number of reps and timeline of them.

In both the sleep pre day 2 and post day 2, Sam spends significant portions of time below 90 mg/dL and some below 60 mg/dL. Such a response might be related to the significant workloads she had on consecutive days or on her pre-bed meal routine. Insulin kinetics and action overnight, induced by the pre-bed meal(s), likely heavily influence overnight glucose control.

Figure 2: Sam’s Glucose Data from Day 2 of the CrossFit Games Semis

Day 3

Workout 5

For time:

2,000-m row

60-m handstand walk

5 legless rope climbs

1,000-m row

40-m handstand walk

4 legless rope climbs

500-m row

20-m handstand walk

3 legless rope climbs

Time cap: 30 min.

Result: 3rd (24:37)

Sam absolutely annihilated this workout. And given it was a heavy upper body workload, this should be no surprise. (Her Instagram handle is @bicepslikebriggs.) The length of this workout (Figure 3) and the more distributed and uniform intensity demands could partly explain the smoother and relatively lower glucose levels during exercise.

Workout 6

10 rounds for time of:

3 clean and jerks

3 bar-facing burpees

Time cap: 7 min.

Result: 6th (2:50)

This is the sprint finisher: 3 minutes of gut wrenching big lifts followed by burpees. The work involved in moving a barbell from the ground overhead and then the body to the ground and back is exceptional. Unfortunately, this event wasn’t captured in Sam’s glucose data for technical reasons.

Figure 3: Sam’s Glucose Data from Day 3 of the CrossFit Games Semis

As mentioned earlier, glucose will rise in response to the mixture of intensity and duration. However, very short efforts, like used in traditional Olympic style weightlifting training or short strength training sessions, are very high intensity, but work duration is much too short to influence glucose dynamics. This holds true even with relatively short rest periods, though this is probably a continuum where increasing the work duration of a set while decreasing rest periods will eventually cause glucose to rise. Remember: This is an energy system-related phenomenon and such short training styles predominantly emphasize the phosphagen/creatine phosphate energy system pathways rather than glycolytic or oxidative pathways.

We are excited to continue to work with Sam on her future goals (and not just for the data!)