The hundred-plus people assembled in the open field make an unlikely group. From women in headscarves to those sporting trendy figure-hugging leotards; middle-aged men to corporate slickers and even a gangly 12-year-old -- there is only one thing binding this odd assortment of individuals together, and that’s the fear of the trainer. One missed lunge or one ill-timed squat would bring the wrath of the group leader unto them; and no one wants to be shamed for having the form of a lazy five-year-old.

Welcome to the world of fitness bootcamps - a craze that’s taking the country by storm. Bootcamps have been popular the world over for a while now, given their military-style approach to weight loss which combines a series of simple exercises into rapid rounds. Pakistan has witnessed a recent proliferation in such programmes, the majority of which are based on High-Intensity Interval Training or HIIT, a form of exercise that is having a serious moment worldwide.

From super athletes like David Beckham to Victoria’s Secret supermodels, celebrities around the globe favour this form of intense workout to fulfill their fitness goals.

So what exactly is HIIT? It’s a type of cardiovascular exercise that alternates short bursts of high intensity activity with equally short ‘rest’ or ‘recovery’ periods. Because of its ability to burn fat and build muscle, it’s considered a healthier alternative to traditional exercises such as running for hours on the treadmill.

Originating out of Karachi in 2013, the increasingly popular 42-Day Challenge can be credited for pioneering the bootcamp trend. Developed by medical student Torsam Tajik and aspiring lawyer Nusrat Hidayullah, the 6-week programme combines an intensive workout routine with an equally stringent diet plan. Making its way to Lahore only last year, the challenge has found a willing and ready audience in a city that’s renowned for its unhealthy eating habits.

The popularity of this, and similar programmes, proves that the newfound fondness for fitness is anything but a passing fad, says Natasha Qizalbash, founder of 180 Degrees which runs the 30- and 40-Day Bootcamps in Lahore and Islamabad. "The widespread use of social media has meant that people are so much more aware than they were a decade ago and they want to adopt worldwide practices that they see as beneficial. Pakistan has seen a recent shift towards farmers’ markets and organic produce because people want to eat healthy; that’s translated into a desire to be fit and live a better lifestyle. Bootcamps are popular because they are an effective way of achieving this goal."

Those that opt for the gruelling sessions are often those who have given up on regular diets and gym visits because of a lack of results. "I’ve tried virtually every fad diet that comes out and I have spent months running on a treadmill daily; but after two kids my weight was stuck at an unhealthy figure," says Rabia Anwar Khan, a participant of the 40-Day Bootcamp. "This programme literally gave me the kick in the gut that my system needed and I managed to drop eight kilogrammes in six weeks."

Bootcamps have an inherent appeal to those looking for a disciplined and streamlined approach to fat loss, with their clearly defined exercise routines and complementing meal plans designed to address one’s body requirements and fitness goals. "I love the bootcamp because as a complete exercise novice, it feels great to be in the hands of experts and be told exactly what to do," says one participant. "In a gym, it’s easy to give up the minute you start breaking a sweat, but here, the trainers force you to keep at it and push your boundaries consistently."

The sessions are presided over by trainers who not only perform the exercises on a raised platform for all to see but also don’t believe in mincing their words when it comes to motivating the class, almost like a drill sergeant. That’s why it’s called a bootcamp -- be ready to experience some tough love, and even be reduced to tears by what seems like an impossible one hour of intense workout.

"Some people might feel like they’ve been thrown in the deep end but in my experience we all tend to underestimate our bodies and their ability to take on challenges," says Qizalbash. "While we are strict about adhering to the routine, we do of course tell people to take it easy when they need to or take into account their limitations."

What happens when the six weeks of bootcamp are over? Do the effects last in the long-term? "The regime is meant to kick start you on a road to a healthier lifestyle," says Qizalbash. "Our goal is to educate people in such a way that once the programme finishes, they are able to incorporate its core principles into their daily lives. Just following the personalised meal plan consistently will continue to yield results, since 80 per cent of weight loss comes from the kitchen."

In any case, Qizalbash maintains that a majority of the people who sign up for the programme return for at least one follow-up session because the camaraderie, the open space and the motivating atmosphere becomes an addictive part of their lives.

The 42-Day Challenge sends its participants home with a workout CD at the end of the 6 weeks, compiled with home-based versions of the exercises in order to offer a sustainable, long-term solution. Anushka Paracha, who runs the programme in Lahore, says one of its biggest successes has been challenging the misconceptions surrounding fitness routines in Pakistan, especially amongst women.

"A majority of the women here tend to follow diets that make them lose muscle strength along with fat, making their bodies weak as a result," she explains. "Another mental block is weight training, because women fear that they will become muscular if they lift dumb bells. We show them that building muscle doesn’t necessarily bulk you up; it, in fact, makes you stronger and improves your quality of life. When they leave the programme, they do so much better equipped to maintain a healthy lifestyle."

No matter which programme you opt for, according to nutritionist Amna Sultan, the key to undergoing such an intense workout challenge is to trust your instincts. "We all know what our limitations are and how much we can push ourselves. In most instances, the workouts cater to those who have physical limitations, such as a bad back, but I would still advise people to watch out for signs that mean the body cannot be pushed any further. Having said that, an exercise that doesn’t challenge you to push your boundaries isn’t working. So be intelligent and listen to your body."