When it comes to marathon training groups, some runners love it and others hate it. It really depends on the personality of the runner. Runners who enjoy the solitude of the trail or road may not enjoy sharing the experience with others. Introverted individuals may feel stressed being around lots of runners. While others thrive on the energy of other runners around them. Neither course is right or wrong. They are just different methods for achieving the same goal.
However, if you're new to marathon training, if you've tried training on your own and just can't seem to stick with it, or if you've run several marathons and feel you've plateaued, then joining a marathon training group may be just what you need. A marathon training group can provide the confidence to cross the finish line the first time, complete the training, or set your next PR.
Determine Your Level
Not all marathon training group programs are alike, so do a little homework before you sign up. Where I coach, there are marathon training groups for for women only, there are marathon training groups catered to the elites, and there are marathon training groups that I coach that support a melting pot of levels. Some programs (even though they're group) cater to the individual by providing training plans designed for each group member's specific needs. Others have everyone on the same plan. Again, there's no right or wrong type of marathon training group, but there may be one that's better suited to your personality and/or running fitness level.
Plan duration is another aspect to consider. If a group is following a 12 to 14-week plan for a full marathon, you can pretty much bet that's a group of highly competitive and experienced runners. Plans centered around a 16 to 20-week time span will better meet the needs of most runners (novice to experienced). Keep in mind that most marathon training group plans assume that you're coming into the training with at least a month's worth of weekly total mileage of about 20 to 25 miles. You need that base before starting any training.
Meshing schedules is another key factor. Find out in advance how many days a week, which days, and at what time the group will meet for the weekly group runs. There's no point in joining a group if you'll only be able to make two of the group runs during the three to four months of training. If you sign up for a group for which you know it will be hard to make the runs, then deep down you're probably not fully committed to the training. That can spell disaster and/or disappointment.