4 technologies to enhance sporting performance

As well as a good pair of run­ning shoes, a well-fit­ting sports bra that effi­ciently sup­ports the breasts is import­ant for female run­ners. It can help reduce breast pain and improve per­form­ance. When the breasts are not prop­erly sup­por­ted, the body com­pensates by pro­tect­ing them in oth­er ways. This com­pens­a­tion can reduce run­ning per­form­ance, increase the risk of injury and even lead to back and chest pain.

To bet­ter under­stand the role of a good sports bra on the bio­mech­an­ics of run­ning, a team of research­ers led by Douglas Pow­ell and Hailey Fong from the Breast Bio­mech­an­ics Research Cen­ter at the Uni­ver­sity of Mem­ph­is (USA) stud­ied how wear­ing a bra impacts knee joint stiff­ness dur­ing exer­cise. This bio­mech­an­ic­al meas­ure­ment provides inform­a­tion on the res­ist­ance of the knee joint to an applied force. To do this, the research­ers recruited 12 non-pro­fes­sion­al female run­ners aged 18–35 and had them wear two dif­fer­ent sports bras: one with high sup­port and the oth­er with low sup­port. A con­trol group did not wear a bra at all.

Each par­ti­cipant ran on a tread­mill equipped with force detect­ors for three minutes. The research­ers filmed the run­ners using a 10-cam­era motion cap­ture sys­tem. Retrore­flect­ive mark­ers placed on the run­ners’ bod­ies also tracked their move­ments. The research­ers then used soft­ware that they had spe­cially developed in this work to cal­cu­late the excur­sions of the knee joint (flex­ions, exten­sions and rota­tions) on the basis of the images they obtained. They also mon­itored chest move­ment dur­ing the exercise.

The exper­i­ments revealed that when breast sup­port was high­er, the knee joint was more rigid, thanks to smal­ler joint excur­sions. Com­pared with the con­trol group, the low- and high-con­tain­ment bras increased knee joint stiff­ness by 2% and 5% respect­ively. Over­all, a high sup­port sports bra appeared to improve run­ning per­form­ance by 7%. The research also revealed that improve­ments in run­ning per­form­ance with high sup­port sports bras was strongly cor­rel­ated with breast size: women with lar­ger breasts benefited more in terms of run­ning performance.

Over the last 50 years, bra design has changed little, explains Douglas Pow­ell: “our res­ults, com­bined with those of pre­vi­ous stud­ies, show that sports bras should be con­sidered not just as appar­el, but as sports equip­ment in their own right.”¹².

In top-level sport, a frac­tion of a second can make all the dif­fer­ence. Made-to-meas­ure insoles can improve sport­ing per­form­ance and research­ers at Empa, ETH Zurich and EPFL, all in Switzer­land, have developed a device that is much more soph­ist­ic­ated than a simple insert. The new insole com­prises pres­sure and shear sensors that can meas­ure these para­met­ers dir­ectly on the sole of the foot dur­ing any type of phys­ic­al activity.

“The pres­sures recor­ded can be used to determ­ine wheth­er a per­son is walk­ing, run­ning, or climb­ing stairs. It’s even pos­sible to determ­ine wheth­er they’re car­ry­ing a heavy load on their back, in which case the pres­sure shifts more towards the heel,” explains Gil­berto Siqueira, pro­ject lead­er and research­er at Empa and ETH­’s Com­plex Mater­i­als Laboratory.

The soles were fab­ric­ated using a 3D print­er, known as an extruder. The base of the sole is made from a mix­ture of sil­ic­one and cel­lu­lose nan­o­particles. A con­duct­ive ink con­tain­ing sil­ver is then prin­ted atop this first lay­er. The sensors, which are piezo­elec­tric, con­vert mech­an­ic­al pres­sure into elec­tric­al sig­nals. These are prin­ted on the con­duct­ing part of the sole, where the pres­sure exer­ted by the foot is greatest. The ensemble is pro­tec­ted by a final lay­er of sil­ic­one. An inter­face for read­ing the sig­nals gen­er­ated, inser­ted into the sole, com­pletes the device.

As well as Empa, ETH Zurich and EPFL, the Centre Hos­pit­al­i­er Uni­versitaire Vau­dois (CHUV) and the ortho­ped­ics com­pany Numo were also involved in this work. Such insoles could be used by ath­letes to meas­ure their pro­gress dur­ing train­ing and their per­form­ance in gen­er­al³.

Research­ers at the Insti­tute of Basic Sci­ence (IBS) in South Korea have developed a new tis­sue pros­thes­is made from a con­duct­ive hydro­gel that can be injec­ted dir­ectly into an injured muscle to regen­er­ate it and recon­nect it to the nervous sys­tem. This pros­thes­is has enabled rats with torn hind limbs to walk again.

Muscle injur­ies such as strains or tears are com­mon sports injur­ies. When a muscle is torn, its elec­tric­al com­mu­nic­a­tion with the nervous sys­tem is dis­rup­ted and it no longer func­tions prop­erly. Today, these injur­ies can be treated using port­able or implant­able elec­tron­ic devices. How­ever, these devices are rigid and inflex­ible, which makes them incom­pat­ible with soft bio­lo­gic­al tis­sue. Not only are these devices uncom­fort­able for the patient, they can even cause inflam­ma­tion, which slows the heal­ing process.

The research­ers’ flex­ible pros­thes­is com­prises a hydro­gel con­tain­ing hya­lur­on­ic acid – a nat­ur­al poly­sac­char­ide with mech­an­ic­al prop­er­ties sim­il­ar to those of soft tis­sue and known for its regen­er­at­ive prop­er­ties. To make the pros­thes­is elec­tric­ally con­duct­ing, they added, via cova­lent bonds, chem­ic­al com­pounds to it con­tain­ing hexagon­al rings that can accom­mod­ate gold nan­o­particles. Gold is also biocom­pat­ible and intrins­ic­ally chem­ic­ally inert.

When the gel is injec­ted into the muscle tis­sue of a rat, the chem­ic­al bonds it con­tains are broken. They quickly re-form once the hydro­gel is fixed in the muscle, how­ever. It is this innov­at­ive chem­istry that enables it to regen­er­ate dam­aged tis­sue. What is more, the gel does not over­activ­ate the animal’s immune sys­tem. It there­fore does not pro­duce fibrous scar tis­sue, as can be the case with con­ven­tion­al implant­able prostheses.

The research­ers found that the hydro­gel adheres to the peri­pher­al nerves of the injured muscles in the rat’s hind leg. This means that the device can be con­nec­ted to elec­tric­al wires and the sci­ent­ists are able to activ­ate the muscle by send­ing elec­tric­al stim­u­la­tion through the gel. Repeated stim­u­la­tion enabled the rodents to walk shortly after an injury.

Ulti­mately, the research­ers would like to apply their tech­nique to human muscle. How­ever, before they can do this, they will need to carry out stud­ies on anim­als lar­ger than rodents to determ­ine wheth­er the hydro­gel can con­duct elec­tri­city over longer dis­tances⁴.

Research­ers in France have meas­ured the speed of pro­gres­sion, rota­tion and rebound angle of a table ten­nis ball off a glass sur­face. Led by Jean-Chris­tophe Géminard, CNRS research dir­ect­or at the phys­ics labor­at­ory of the ENS in Lyon, the sci­ent­ists fired the ball onto a glass plate while vary­ing the angle and impact speed of the ball. They then meas­ured the above para­met­ers by ana­lys­ing videos of how the ball inter­ac­ted with the plate.

The res­ult: at angles of incid­ence typ­ic­ally less than 45 degrees, the ball rolled (without slid­ing along the sur­face of the plate) com­plet­ing a frac­tion of a full turn, that is, less than one turn, before rebound­ing. At high­er angles of incid­ence, the ball still slid as it left the sur­face, redu­cing its rota­tion after the bounce. The research­ers explain that when boun­cing off a sol­id sur­face, such as a glass plate, the final rota­tion, speed and bounce angle of the ball are gov­erned solely by the fric­tion between the ball and the sur­face. This res­ult, they say, would be the same for a ball boun­cing off a real ping-pong table.

To make their exper­i­ments more real­ist­ic, Jean-Chris­tophe Géminard and his col­leagues then repeated them using a rack­et covered with a stack of foam and elast­omer. To a cer­tain extent, this scen­ario pre­ven­ted the ball from slid­ing over the sur­face of the glass plate. Play­ers cap­able of repro­du­cing the tech­niques described in this study will undoubtedly have a sig­ni­fic­ant advant­age, say the researchers.

Finally, the sci­ent­ists repro­duced their exper­i­ments on sur­faces com­monly used by table-ten­nis play­ers in the real world, but to date the res­ults of this part of their work have not yet been made pub­lic⁵⁶.

Isabelle Dumé