• Workouts that combine strength training with a high heart rate can help you save time in the gym.
• A trainer said his go-to workouts help to build muscle and improve stamina in less than 20 minutes.
• Strategies like workout ladders, EMOMs, and weight complexes can make exercise more efficient.

A smart fitness plan can help you build muscle, burn fat, and improve your health all at once — and kettlebells are an ideal tool for the job, according to a personal trainer.

"I like to describe the kettlebell as sort of the Swiss army knife of functional fitness," personal trainer Pat Flynn, who specializes in kettlebell training, told Business Insider. "It's like the ultimate secret weapon."

Kettlebells can be more dynamic than other types of strength training, making them well-suited for getting the most athletic benefits in the least amount of work.

Flynn shared his favorite "pocket-sized" workouts with kettlebells that are simple, don't take much time, and build full-body muscle while elevating heart rate for cardio benefits and better calorie burn.

Three workouts a week is enough for most people, he said. Combined with a quick warm-up for better mobility and performance, they take around 15 to to 20 minutes; less time than catching up on your favorite TV show.

Save time with a ladder-style workout

One of Flynn's go-to ways to work out is doing two exercises one after another, increasing the number of reps of one movement and decreasing the reps on the other to move up the "ladder."

For example:

• 10 reps of a two-handed kettlebell swing and one push-up
• Nine swings and two push-ups
• And so on …
• …ending after a round of one swing and 10 push-ups

The ladder uses a strategy called a superset, performing exercises back-to-back with minimal rest, cutting down on workout time. In this case, it involves using different muscle groups with each move, so that you're resting your legs while your upper body is working, and vice versa.

An 'EMOM' workout keeps you moving

Flynn said he often uses a timed workout called an EMOM, which stands for "every minute on the minute."

To do it, set a running clock. At the beginning of every minute, complete a set of exercise such as:

• 10 kettlebell swings

or

• 10 goblet squats

Rest for the remainder of the minute. Repeat for 10 to 15 minutes.

The built-in rest offers some time to recover while still keeping up the pace enough to raise your heart rate, combining the benefits of cardio and strength training.

If that's too intense, try an alternating EMOM, swapping in a less intense movement like a 20-second plank hold for every other round.

Working out on the clock can help you maintain a high intensity, burning calories while also performing strength exercises so you're building muscle to burn even more energy over time, according to Flynn.

"You'd be better off in terms of bang for buck performing what's called metabolic resistance training," he said. "One of the best ways to get leaner is actually try to focus on being stronger and a bit more muscular as well."

Kettlebell complexes combine multiple exercises efficiently

Flynn likes combining movements together into a workout complex, which means transitioning from one exercise to the next without putting the weight down.

One example:

• 5 single-arm kettlebell swings (with one kettlebell)
• 5 single-arm cleans
• 5 single-arm presses
• 5 squats
• 5 lunges
• Repeat on the other side

A complex is great for increasing your intensity and getting work done in less time. Beginners should master the basic moves first before trying a complex, since you need to be comfortable switching seamlessly between moves (and sometimes doing more advanced moves).

Flynn also likes the Armor Building Complex, a similar workout created by Dan John, a strength and conditioning coach with decades of experience.

With a kettlebell in each hand, perform:

• Two cleans
• One military press
• Three front squats

Repeat for a set time (say, five to 10 minutes) as long as you can maintain good form.

The rep pattern helps make sure that the bigger muscle groups like your legs are working as hard as your arms with the same weight, avoiding a common mistake in HIIT-style workouts.

The end result is a workout that offers a little bit of everything for overall fitness in a short amount of time.

"We just want to be really well-rounded, right?" Flynn said. "We want to have a good amount of strength, lean functional muscle, healthy body fat percentage, mobility, and not get injured."

• A bodybuilder said he stopped skipping warm-ups, and it's led to better results in the gym.
• A 5-minute warm-up can help improve muscle activation and reduce injury risk.
• Adding weights to a warm-up can lead to better performance, research suggests.

A bodybuilder said a four-part warm-up with some weightlifting helps him get the most out of his workouts to build muscle and strength.

Andre Adams, a National Academy of Sports Medicine Master trainer, competes in the International Federation of Bodybuilding pro league.

Adams said taking even a few minutes to warm-up and working in a few sets of moderate weight can translate to better movement.

This can be especially important for anyone hitting the gym after working at a desk job, since sitting all day can create tension and muscle imbalances.

"Skipping a warm-up is way more common that you think. I've been guilty of it too, everyone's on a time crunch," he told Business Insider said. "It doesn't have to be lengthy, it can be five minutes, it's just performing the right movements for the workout."

A quick four-part warm-up includes foam rolling and body weight exercise

Adams said typically spends about five minutes warming up with muscle activations, followed by five minutes of light cardio.

Jumping right into a workout can increase risk of injury, which may not happen right away but can build up over time, causing persistent aches and pains.

A warm-up is also important to prepare the muscles and joints to work effectively so you can maintain the highest quality movement possible.

"When I was younger and my body was much more resilient I would often times skip warm-ups all together and get away with it. However, over time as I aged this lead to pain, muscle imbalances, unproductive workouts and ultimately injuries and setbacks," he said.

Now he warms up by following four steps recommended by the NASM:

Inhibit — the first step is to reduce tension and calm down overactive or tight muscles, usually by foam rolling.

Lengthen — next is some stretching, which can be static (holding a stretch) or dynamic, with movement. For a typical leg day, Adams said he might do some standing hip circles.

Activate — priming the right muscle groups, often with bodyweight exercise. To target the glutes for leg day, for instance, Adams does glute bridge marches.

Integrate — putting it all together with compound exercises similar to what you'll be doing in the workout. This can include bodyweight movements like squats. It can (and should) also include exercise with weights, but at a slightly lower intensity than your working sets.

Adding weights to a warm-up can boost performance

A small recent study found athletes who lifted heavier for a warm-up — at 80% of their 10-rep max — were able to lift more during their workout and perform better.

"Making the right decisions during the warm-up can significantly enhance training performance," study author Igor Nasser, professor at the Federal University of Rio de Janeiro, told Business Insider. "In our study, it was clear that the strategy of applying greater intensity during the warm-up sets leads to better outcomes than using lighter loads, which is more commonly practiced."

It confirms what bodybuilders already know — that not going heavy enough on the warm-up can leave gains on the table, according to Adams.

"You haven't activated as much muscle fiber as you could have," he said.

That doesn't mean going all-out. Adams said for a working weight of 200 pounds, a warm-up might involve one set at 100 pounds, following by a set at 150 pounds before the main event.

Taking the time for all parts of the process only adds a few minutes to a workout, and can boost performance, improve range of motion, and prevent injury.

"It's not just making the muscle fibers activate, it's making the body work as a system, and that's why we have to do those four steps," Adams said.