Table 1 Studies concerning bone mass, bone metabolism and cycling participation

Barry et al. (2007) [47]

CYC (20)

M

22 to 45

Competitive level

2-h exercise bout at 60% to 75% VT

Hormones, calcium

Parathyroid was increased after 2 h of cycling.

B: observational

Barry et al. (2008) [43]

CYC (14)

M

27 to 44

>450 h/year

4.9 ± 2.4

Two groups: HIGH and LOW calcium supplementation over 1-year season

DXA

Both groups decreased BMD over 1 year in total hip and subregions, without differences for HIGH or LOW calcium.

A: RCT

Barry et al. (2011) [39]

CYC and TRI (20)

M

37 ± 7.6

-

6.0 ± 6.5

Different calcium supplementation groups over three 35-km trials

DXA, hormones

30% of participants had LS BMD T-score over -1.0. Calcium supplementation attenuates disruption of parathyroid hormone.

A: RCT

Beshgetoor et al. (2000) [41]

CYC (12); RUN (9); CON (9)

F

49.6 ± 7.9

-

-

18 months follow-up

DXA, calcium intake

Femur BMD maintained in CYC and RUN, decline CON. LS BMD maintained RUN, decline CYC and CON. No relationship between BMD and calcium intake.

B: case-control

Brown et al. (2000) [49]

CYC (32)

M/F

16 to 62

Competitive cycling

>2

Two groups: HIGH FAT and HIGH CARBOHYDRATE intake; 12-week intervention

DXA

No differences in fat or lean accumulation between groups. BMD increased in HIGH FAT group.

A: RCT

Campion et al. (2010) [34]

CYC (30)

CON (30)

M

29 ± 3.4

28 ± 4.5

22 to 25 h/week

<1 h/week

-

Cross-sectional

DXA

CYC lower WB, LS, pelvis, femoral neck, upper and lower limbs than CON

B: case-control

Duncan et al. (2002) [21]

CYC (15)

RUN (15)

SWI (15)

TRI (15)

CON (15)

F

16 to 17

≥8 h/week

≥8 h/week

≥8 h/week

≥8 h/week

<2 h/week

3.1 ± 1.8

Cross-sectional

DXA

CYC lower legs BMD than RUN. No differences with CON.

B: case-control

Duncan et al. (2002) [45]

CYC (10)

RUN (10)

SWI (10)

TRI (10)

CON (10)

F

16 to 17

≥8 h/week

≥8 h/week

≥8 h/week

≥8 h/week

<2 h/week

3.1 ± 1.8

Cross-sectional

MRI, DXA

CYC lower cortical CSA, moment of inertia and mid-femur BMD than RUN. No differences with CON.

B: case-control

Fiore et al. (1996) [36]

CYC (14); CAN (18); CON (28)

M

-

-

-

Cross-sectional

DXA

CYC lower WB, LS and pelvic BMD than CAN. No differences with CON.

B: case-control

Guillaume et al. (2012) [38]

CYC (29)

M

26.5 ± 5.3

25,000 to 30,000 km/year

4.5 ± 4

Descriptive

DXA, bone markers

CYC lower LS BMD Z-scores. Bone turnover markers were in a normal range.

B: case series

Heinonen et al. (1993) [19]

CYC (22); ORI (30); SKI (28); CYC (29); WL (18); CON (25)

F

18 to 32

-

-

Cross-sectional

DXA, calcium intake

CYC lower BMD at all sites than WL. No differences with CON. No relationship between BMD and calcium intake.

B: case-control

Hinrichs et al. (2010) [35]

CYC (16)

RUN (37)

TRI (22)

TEAM (62)

POW (45)

BAL (13)

STU (126)

CON (61)

M/F

17 to 30

15 h/week

12.5 h/week

15 h/week

10 h/week

10 h/week

27 h/week

7.5 h/week

-

>4

Cross-sectional

DXA

CYC low values of LS and femur BMD than the other groups

B: case-control

Maïmoun et al. (2003) [25]

CYC (11)

SWI (13)

TRI (14)

CON (10)

M

18 to 39

10.6 h/week

10.7 h/week

15.2 h/week

<2 h/week

-

Cross-sectional

DXA, hormones

CYC and TRI induce androgen deficiency compared to CON, without alteration in BMD

B: case-control

Maïmoun et al. (2004) [24]

CYC (11)

SWI (13)

TRI (14)

CON (10)

M

18 to 39

10.6 h/week

10.7 h/week

15.2 h/week

<2 h/week

9.3 ± 6.8

Cross-sectional

DXA, bone markers, calcium intake

CYC lower BAP than all groups. No differences in BMD. No relationship between BMD and calcium intake.

B: case-control

Medelli et al. (2009) [29]

CYC (73)

CON (30)

M

25.8 ± 4.3

28.3 ± 4.5

≥3 to 6 h/day

<1 h/week

-

Cross-sectional

DXA, calcium intake

CYC had higher calcium intake and lower LS and femoral neck BMD than CON.

B: case-control

Medelli et al. (2009) [4]

CYC (23)

M

28.5 ± 3.9

≥3 to 6 h/day

-

Descriptive

DXA

Two-thirds of participants had lower values of LS BMD

B: case series

Morel et al. (2001) [27]

CYC (47); other sports (657)

M

30

7 h/week

-

Cross-sectional. Sportsmen classed as amateur when 11 to 18 years old.

DXA

No differences between different sports

B: case-control, retrospective

Nevill et al. (2004) [23]

CYC (16)

CON (15)

Others (90)

M

28.6 ± 6

24.9 ± 5.4

-

>4 h/week

-

-

>3

Cross-sectional

DXA

CYC had no differences in BMD compared to CON, as other sports do

B: case-control

Nichols et al. (2003) [32]

Young CYC (16)

Master CYC (27)

CON (24)

M

31.7 ± 3.5

51.2 ± 5.3

51.2 ± 2

≥10 h/week

≥10 h/week

<2 days/week

10.9 ± 3.2

20.2 ± 8.4

-

Cross-sectional

DXA

Master CYC lower WB BMD than young CYC. Master CYC lower LS and hip BMD than young CYC and CON.

B: case-control

Nichols et al. (2010) [42]

CYC (19)

CON (18)

M

50.7 ± 4

50.7 ± 4.1

11.1 h/week

4.5 h/week

27.5 ± 6.8

Longitudinal, 7-year follow-up

DXA

Higher percentage of CYC osteopenic/osteoporotic than CON. Greater increment in this percentage in CYC.

B: case-control

Nikander et al. (2005) [26]

CYC (29)

SWI (27)

VOL (21)

HUR (24)

SQU (20)

SOC (19)

SKA (15)

AER (27)

WL (19)

ORI (29)

CRO (25)

CON (30)

F

20 to 30

10.2 ± 6.8

13.5 ± 4.5

9.9 ± 2.5

9.1 ± 2.4

6.0 ± 3.1

8.6 ± 5.5

6.4 ± 3.6

6.6 ± 3.7

8.3 ± 2.6

8.6 ± 1.4

10.9 ± 1.2

2.9 ± 2.0

5.9 ± 3.1

10.6 ± 4.3

8.6 ± 3.3

10.4 ± 3.0

6.4 ± 4.7

10.7 ± 3.8

9.4 ± 7.2

8.3 ± 2.7

3.3 ± 1.3

13.0 ± 3.1

10.7 ± 3.5

-

Cross-sectional

DXA, calcium intake

CYC and SWI no differences with CON in BMD and CSA, as the rest of the sports. No differences in calcium intake.

B: case-control

Olmedillas et al. (2011) [40]

CYC (21)

CON (23)

M

15 to 21

10 h/week

4 h/week

2 to 7

Cross-sectional

DXA

CYC lower BMC at WB, pelvis, FN and legs, and lower BMD at pelvis, hip and legs. Greater differences in CYC over 17 years compared to CON.

B: case-control

Penteado et al. (2001) [22]

CYC (31)

CON (28)

M

24

26

21 h/week

0

5.2 ± 3.3

Cross-sectional

DXA

No differences with CON.

B: case-control

Rector et al. (2008) [37]

CYC (27)

RUN (16)

M

20 to 39

≥6 h/week

≥6 h/week

>2

Cross-sectional

DXA, bone markers

CYC lower WB and LS BMD, and 7 times more likely to have osteopenia than RUN. No differences in bone turnover markers.

B: case-control

Rico et al. (1993) [20]

CYC (22)

CON (27)

M

16

≥10 h/week

-

>2

Cross-sectional

DXA, calcium intake

CYC lower legs BMC than CON, without adjustment. No differences when adjusting by weight. No relationship between BMD and calcium intake.

B: case-control

Rico et al. (1993) [50]

CYC (22)

CON (27)

M

16

≥10 h/week

-

>2

Cross-sectional

DXA

CYC lower WB BMC and BMD than CON

B: case-control

Sabo et al. (1996) [30]

CYC (6)

WL (28)

BOX (6)

CON (21)

M

21 to 24

3,000 to 10,000 km in pre-competition

-

Cross-sectional

DXA

CYC lower LS BMD than CON

B: case-control

Stewart et al. (2000) [31]

CYC (14)

RUN (12)

RUN+CYC (13)

CON (23)

M

18 to 43

8.7 h/week

10.7 h/week

9.4 h/week

0 h/week

>2

Cross-sectional

DXA

CYC lower LS BMD than CON. RUN higher WB BMD than CON. RUN+CYC higher WB BMD than CON.

B: case-control

Smathers et al. (2009) [33]

CYC (32)

CON (30)

M

20 to 45

≥1 year

3 days/week

9.4 ± 1.1

Cross-sectional

DXA, calcium intake, hormones

CYC higher calcium intake. No differences for testosterone. CYC lower LS BMD than CON.

B: case-control

Warner et al. (2002) [28]

Cross-country CYC (16)

Road CYC (14)

CON (15)

M

20 to 40

≥10 h/week

≥10 h/week

<2 h/week

5.9 ± 2.8

9.9 ± 4.4

-

Cross-sectional

DXA, hormones

Cross-country CYC higher BMD at all sites that road CYC and CON. No differences in testosterone levels.

B: case-control

Wilks et al. (2009) [46]

Sprint CYC (52)

Distance CYC (19)

CON (32)

M/F

30 to 82

50 ± 13

<2 h/week

26 ± 15

29 ± 16

Start age

Cross-sectional

pQCT

Sprint CYC higher index of strength in tibia and radius than CON. Distance CYC higher tibial BMC than CON.

B: case-control