A gruelling schedule of sprints and circuits faces these Royal Marine recruits as they climb ropes, repeat rigorous crunches and test their fitness – and this is just their first nine weeks in training.
The recruits are put through their paces as instructors fire commands at them at the Commando Training Centre at Lympstone in Devon.
Their strength and sharpness are put to the test before they go on to complete their training in weeks 10-32.
In this video, recruits from 252 Troop and 253 Troop are filmed as they carry out a demanding series of exercises to improve their discipline, posture, core strength and rope-climbing skills as part of the Initial Military Fitness (IMF) programme.
It's the staple exercise regime given to all the regiment's recruits, which aims to transform them from civilian to disciplined, fit and robust Royal Marine.
Some of the training, like carrying out tough exercises suspended mid-air after climbing halfway up a rope, dates back to the days when Royal Marines were first on ships but they are just as applicable to today's requirements, especially in maritime operations.
This military fitness training at the centre in Lympstone, also known as CTCRM, near Exmouth, is based on a system developed in Sweden in the early 1800s and has been used by the Corps for more than 100 years.
Corporal Daniel Benson, Physical Training Instructor, is heard telling the recruits that if they carry out the exercise sequence correctly, they will move on. Otherwise, they keep repeating it.
The training schedule is also designed to get their "sharpness of mind" ready for their role.
If they can get it right here, they can get it right on the battlefield – and this prepares them for later Commando tests.
The fitness training is highly-synchronised and all movements are done in time to the Physical Training Instructors commands.
The recruits are working together towards a final pass-out display assessed by the Physical Training and Sports Officer (PTSO) in week nine.
The exercises include warm-ups, rope climbs, a sit up sequence, a lap of the Commando Training Centre, pull-ups and finally, a sprint session.
Captain Wayne Grounsell, the PTSO at Commando Training Centre, said: "IMF progressively prepares each individual as they come into Royal Marines training.
"It is to prepare them for the rigours to come later on in training and ultimately to prepare them for the Commando tests."
From week 10 of Royal Marines training, the recruits move on to advanced military fitness on an assault course, referred to in the Marines as the Bottom Field.
Here, they have to carry a rifle and equipment weighing 14kg while they perform a series of tough exercises, including a 30ft rope climb and carrying each other across their shoulders for 200 metres, among others.
This prepares them for the weeks ahead, culminating in a test in week 20 of training.
From week 26, the recruits enter the Commando phase, preparing them for the Commando Tests which have not changed in more than 50 years.
During this phase, the recruits run everywhere on the Marines training base.
"IMF is all own-body weight fitness," said Capt Grounsell. "It has evolved from a school of very hard experience over the years. IMF derives from the Swedish PT system. It builds strength, coordination and fitness."
At week nine the recruits have to pass an IMF test.
If recruits fail the IMF test at week nine, they enter Hunter Company, the rehabilitation centre which is considered to be one of the best in the military, until they are ready to re-enter recruit training.
"There is no point testing them too early or before the body has been able to adapt, which is why they are tested at week nine when they peak," adds Capt Grounsell. "It really fosters a good team spirit and good competition between the individuals within the Troop."
This video feature was filmed and edited by Richard White who is a student at the Forces Media Academy, a creative media course run by SSVC for service leavers, veterans or reservists.
Applications are open for courses this September, with £18,000 bursary from the Royal British Legion.
More information on the Forces Media Academy can be found here.