Starting in the front of a mass start can mean good position but a rough swim.
Let's focus on the section of the swim that typically causes the greatest anxiety: the start.
Getting Into the Groove
Although in most triathlons the swim is relatively short, it nonetheless can be the cause of considerable apprehension. Much of this uneasiness can be traced to the often-chaotic start, where athletes frequently struggle with feelings of disorientation and claustrophobia as pre-race angst gives way to an early adrenalin surge and hundreds of swimmers jockey for position.
A good start means a better opportunity to catch a faster draft and start the ride in a comfortable position. Generally, there are three different types of starts: deep water (floating) beach start (on the beach, or ankle-to-knee deep) and dive starts.
For a deep-water floating start, your heels should to be close to the surface of the water and behind you immediately prior to race start. Practice floating and sculling in place followed by a whip kick or side scissor kick to quick-start your acceleration once the cannon sounds.
For beach starts, run until the water is knee high, then dolphin dive. As you run, do not drag your feet through the water, rather, lift them completely above the water for as long as possible, and even try and squeeze in one extra step if you can, like an Olympic hurdler clearing that last hurdle, before the final dive in.
Be sure to inspect the terrain before the race to check for any sinkholes or rocks. Then dive in hands first, not belly first. For knee- or waist-deep starts, jump and dive into the water with your arms in a tight, streamlined arrowhead position over your head. Rely on a strong kick to get you going.
Last, you can practice dive starts in the pool. Keep your hands together in a tight, streamlined entry and your head down so your goggles don't come off. Try not to sight at all for the first 50 to 75 meters, and you will break out of the crowd that much more quickly.
Finding Your Pace
The pacing of the start is critical as well. You need to assess your strengths in relation to the race distance. When competing at an Olympic- or sprint-distance race, the swim pace tends to be higher, and the outcome of the swim is more critical to your overall success than if you are racing a long-course event.
If you have a lot of natural top-end speed in the pool but are relatively less efficient at distance swimming, start your swim at 85 to 90 percent of your max 50-meter speed for the first 50, then drop to 80 to 85 percent for the next 50. This should still be relatively faster than much of the field but will leave you with enough in reserve to catch onto the feet of those efficient long-distance pace swimmers.
Alternately, if you are an efficient endurance swimmer but lack a lot of sprint speed, practice starts at closer to 90 to 95 percent of maximum speed in training, with the second 50 meters at 85 to 90 percent. Well-trained endurance athletes tend to be efficient at flushing lactic acid, so a closer-to-max effort shouldn't hurt you too much but will help put you in a position that allows you to maximize your big aerobic engine.
Take note that, at 200 meters, you may feel quite fatigued, but with practice and experience you will learn if you are tough through this section then you can work into a good rhythm for the balance of the race.
Pacing for Ironman-distance racing is slightly different. Because of the sheer volume of athletes that typically begin together in a mass start, there are always a lot of drafting opportunities. While a crisp start is still important, it should be backed off to no more than 70 to 75 percent of max effort.
When you're going long, race-start position is much more critical. For competitive reasons it is better to slightly over-seed yourself. This allows for stronger swimmers to come through and more opportunity to hop on a passing train. Be forewarned that this may also increase chances for a rough swim, so if you goal is to finish and be comfortable, start at the outside of the field and further back.