The Effects of Low Energy Availability and High Impact Jumping on Markers of Bone (re)Modelling in Females
Condition: Bone Resorption; Bone Atrophy; Energy Supply; Deficiency; Female Athlete Triad; Relative Energy Deficiency in Sport
MeSH terms: Bone Resorption; Female Athlete Triad Syndrome; Relative Energy Deficiency in Sport
Study type: Interventional

Summary: 
      Osteoporosis is worldwide health epidemic categorized by poor bone health, primarily
      diagnosed by low bone mineral density, and costs healthcare systems billions every year.
      Athletes and exercising people who expend large amounts of energy in physical activity, or
      restrict diet in order to lose weight, are at risk of low energy availability. This is when
      an individual fails to match their exercise energy demand with a appropriate dietary intake
      in order to maintain optimal physiological function; which can lead to low bone mineral
      density, osteoporosis both early and later in life and an increased risk of injury. Runners
      are particularly susceptible to stress fracture in response to low energy availability due to
      repetitive ground impact. Research shows that as little as five days low energy availability
      significantly reduces bone formation, and significantly increases bone resorption, in
      physically active women. The ideal solution is to restore energy availability; however, this
      is often very difficult during periods of intense training and conflicts with the goal of
      weight loss. Therefore, there is a need to develop an alternative tool to protect bone
      health. It is critical that any exercise intervention does not further reduce energy
      availability as previous research shows that this accelerates bone loss rather than prevents
      it. Low repetition high impact jumping exercise is highly beneficial to bone health and has
      been shown to improve bone structure when used as a long-term intervention in energy replete
      states. It takes very little time to complete and uses a very small amount of energy.
      However, no study to date has examined the effects of such an intervention during low energy
      availability. The current study will investigate whether low repetition high impact jumping
      prevents or reduces the reduction in bone formation and the increase in bone resorption
      experienced during five days of low energy availability and findings will have implications
      on athletic and recreational training recommendations in order to protect bone health.
    

Detailed description: 
      Participants will complete two four-day experimental conditions within the first seven days
      of two separate menstrual cycles. These will be preceded by a four-day baseline assessment
      period. There are three experimental conditions in total: control (CON), low energy
      availability (LEA) and low energy availability and high impact jumping (LEA+J). Participants
      will be randomly allocated to complete the control condition and either the LEA or LEA+J
      condition. The order in which the two conditions are completed will be randomized and
      counterbalanced. In total, fifteen laboratory visits will be required per participant:

      Baseline assessment (four days and one visit):

      Visit 1:

      Participants will come to the laboratory to complete the informed consent procedure on day 1,
      once they have had at least 24 hours to consider the participant information sheet. Providing
      informed consent is given, participants will complete three questionnaires (a health screen,
      the Low Energy Availability in Females Questionnaire and the International Physical Activity
      Questionnaire) which include questions regarding their medical and injury history, dietary
      habits, menstrual cycle and physical activity habits. They will then have their height and
      weight taken. Provided the responses and measures confirm that the participant meets the
      inclusion and exclusion criteria, they will then undergo familiarization of resting metabolic
      rate assessment where they will lay supine in a dimly lit room whilst expired gas is
      collected via a mouthpiece. During familiarization the researcher will check for signs of
      hyperventilation. Following that, the participants will be familiarized with a jumping
      exercise routine if the participant is randomized into the group that will be performing this
      routine during an experimental condition. Finally, the participant will be asked to complete
      an incremental exercise test to volitional exhaustion on a treadmill whilst expired gas is
      collected and analysed using a metabolic cart, and heart rate and rating of perceived
      exertion are taken, as a measure of aerobic fitness.

      For the following three days (2, 3 and 4), participants will be instructed to self-report
      weighed energy intake using a set of scales provided and a food diary according to the
      instructions on the diary itself which the researcher will read through with the participant.
      They will be asked to eat according to their usual dietary habits and return it
      electronically at the end of day 4, or during a subsequent visit. Participants will also be
      provided with a tri-axial accelerometer (Actigraph GT3X+) device and instructed to wear it
      around the waist for the entirety of days 2, 3 or 4 (apart from when bathing and washing).
      They will be not required to visit the laboratory on days 2, 3 or 4.

      Experimental conditions (four days and four visits, per condition):

      The following will outline the experimental protocol assuming the participant is completing
      the LEA+J condition followed by the CON condition, and end with a description of how the
      protocol differs should they be randomly allocated to complete the LEA condition as opposed
      to the LEA+J, condition. Participants will be required to refrain from exercise which is not
      part of the study for the entirety of all experimental conditions.

      LEA+J condition:

      Participants will be required to notify the research team at the onset of their next menses
      and will commence the experimental condition the following day, or the day after that if the
      participant is not able to do what is required of them the following day. From the first
      until the last day of each condition, participants will be required to wear the Actigraph
      device at all times apart from when bathing and washing. Participants will be instructed to
      record their diet during day 1, as they did during days 2, 3 and 4 of the baseline condition,
      and will be asked to eat according to their usual dietary habits but instructed to make
      choices that they will be able to replicate ahead of each subsequent experimental condition.
      They will not be permitted to drink caffeine or alcohol.

      Visit 1:

      Participants will be required to collect their final meal on day 1 from the laboratory and
      will be instructed to eat it at exactly 20:00. They will complete the Pittsburgh Sleep
      Quality Index (PSQI; a questionnaire regarding sleep habits and quality during the last
      month). They will also be instructed to refrain from any other food or drink, other than
      water, for the rest of the evening. Participants will be provided with a self-report water
      intake record sheet and water bottle from which to drink and instructed to report daily water
      intake from the start of day 2 until the end of the condition. They will also be provided
      with a small container suitable to collect a urine sample upon waking the following morning.
      Participants will be instructed to bring the sample with them to the laboratory, where it
      will be analysed and disposed of immediately.

      Visit 2:

      On day 2 of the first condition, participants will be required to arrive at the laboratory
      between 06:00-09:00 without eating breakfast or ingesting caffeine for at least 18 hours
      prior. The participant will be asked to travel by car or by public transport and restrict
      walking distance as much as possible. Weight and body composition will be taken in shorts and
      underwear using scales and bio-electrical impedance. The investigators will then perform a
      resting metabolic rate assessment and a series of cardiovascular measures using pressure
      cuffs, tonometry and electrocardiography. A venous blood sample will be split into plasma and
      serum separation Vacutainers from the arm by a phlebotomy trained researcher using standard
      venepuncture methods. The participants will then be instructed to complete a brief high
      impact jumping exercise routine on a Kistler force platform with demonstrations by the
      researcher and continued feedback to maintain optimum form. All jumps will be performed
      barefoot. The investigators will then provide a breakfast to consume in the laboratory along
      with a multivitamin multi-mineral tablet. The food the participants are required to eat for
      the rest of the day will be packed into a cool box to take away and the participants will not
      be permitted to consume anything which is not provided within the cool box, other than
      "calorie-free" drinks (black coffee, black tea, green tea, etc.). The participants will be
      instructed to perform a similar jump routine at home at least 8 hours after the morning jump
      routine. All jumps will be performed barefoot.

      Visits 3 and 4:

      On days 3 and 4, participants will be required to arrive at the laboratory between
      06:00-09:00 without eating breakfast. Participants will return any uneaten food from the
      previous day and report any items consumed (other than "calorie-free" drinks) that were not
      part of the cool box provided. The participants will complete the morning jump routine and
      have their prescribed breakfast with multivitamin and multi-mineral tablet at the laboratory,
      before leaving with the rest of their food for that day packed in a cool box. The
      participants will not be permitted to consume anything which is not provided within the cool
      box, other than "calorie-free" drinks. The participants will be instructed to complete the
      evening jump routine - as on day 2.

      During day 4, participants will only be permitted to drink water and will be instructed to
      consume their final meal at 20:00 and refrain from any other food or drink (other than water)
      for the rest of the evening. At the end of day 6, the participants will also be provided with
      a small container suitable to collect a urine sample upon waking the following morning.
      Participants will be instructed to bring the sample with them to the laboratory, where it
      will be analysed and disposed of immediately.

      Visit 5:

      On day 5, participants will repeat the same process as on day 2, except will be required to
      arrive at the laboratory at the exact same time rather than anywhere between 06:00 - 09:00
      and they will not complete the morning or evening jump routines, the PSQI or be given
      breakfast, a multivitamin multi-mineral tablet nor food to take away.

      Participants will be provided with an ovulatory test kit to take away and use once per day
      (urinate on a stick as per a pregnancy test) for up to 8 days in the middle of the menstrual
      cycle. Once a positive test is observed the participants will report this to the research
      team and if no positive is reported within 8 days this will also be reported to the research
      team.

      CON condition:

      Visits 1-5:

      Participants will again be required to notify the research team at the onset of the next
      menses (following the end of the LEA+J condition) and will commence the CON condition the
      following day, or the day after that if the participant is not able to do what is required of
      them the following day. The same procedure as in the LEA+J condition will be repeated,
      however, rather than recording their diet during day 1, participants will be instructed to
      repeat what was previously recorded. Also, the total energy intake in the food provided in
      the LEA+J condition will be a third of that provided in the CON condition and participants
      will not take a multivitamin multi-mineral tablet or be required to perform morning or
      evening jump routines.

      How will the protocol differ for participants completing the LEA condition?

      The procedure for the LEA condition is the same as in the LEA+J condition, however,
      participants will not be required to perform morning or evening jump routines.
    

Intervention name(s): Low energy availability; High impact jumping
Intervention type(s): Behavioral; Behavioral
Intervention description(s): Participants will be provided with food to eat every day and will not be permitted to consume any other calorie containing foods or beverages. This amount of energy contained within the food provided will be one third of that contained in the food provided in the control condition (45 kilo-calories per kilogram of fat-free mass per day) and will be standardized between and within participants for carbohydrate, protein and fat composition.; Participants will perform a brief session of high impact jumping every morning (10 maximum effort vertical counter-movement jumps, and 5 maximum effort lateral drop jumps in each direction) and a similar session of high impact jumping every evening (20 maximum effort vertical counter-movement jumps).
Other intervention name(s): Energy restriction
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: All participants will complete the control condition and one of two experimental conditions in a randomized and counterbalanced crossover design.
Masking: None (Open Label)
Primary purpose: Prevention
Keywords: Low energy availability; Energy restriction; Bone (re)modelling; Bone metabolism; High impact exercise