The most important time to work hard is right at the beginning of the swim. You'll burn a lot of energy, but getting into a good position in the pack—near the outside and with a group that swims as fast or a little faster than you can—will save you energy in the long run because you'll be able to do more swimming and less battling.
Of course, to get yourself into the sweet spot within your pack of swimmers, you need the ability to surge in the water, sometimes several times, and then recover while maintaining a strong pace.
The final few weeks leading up to your event are a good time to work on this because the workouts are relatively short and fit well into most athletes' tapering programs. I like to have my athletes perform the following workout twice a week in the three to four weeks before a goal event.
Nick White's Surge-Power Workout:
Warm-up: 500 yards
Drills: 400 yards total
• 3 x 50 yards catch-up
• 3 x 50 yards kick-on-side arm out with fins
• 100 yards sighting drill
Power-interval set: 1,600 Yards
• 8 x 200 yards. Intervals 1-4 pull with paddles; 5-8 swim focusing on high elbows and catch
Sprint-interval set: 900 Yards
• 9 x 100 rotating a 50-yard sprint through the set
• Interval No. 1: 50 sprint, 50 race pace
• Interval No. 2: 25 race pace, 50 sprint, 25 race pace
• Interval No. 3: 50 race pace, 50 sprint
Cool-down: 150 yards